feat: wip pdf authoring

[Kelketek]

Description

Describe what this pull request changes, and why. Include implications for people using this change.
Design decisions and their rationales should be documented in the repo (docstring / ADR), per
OEP-19, and can be linked here.

Useful information to include:

• Which user roles will this change impact? Common user roles are "Learner", "Course Author",
  "Developer", and "Operator".
• Include screenshots for changes to the UI (ideally, both "before" and "after" screenshots, if applicable).

Supporting information

Link to other information about the change, such as GitHub issues, or Discourse discussions.
Be sure to check they are publicly readable, or if not, repeat the information here.

Testing instructions

Please provide detailed step-by-step instructions for manually testing this change.

Other information

Include anything else that will help reviewers and consumers understand the change.

• Does this change depend on other changes elsewhere?
• Any special concerns or limitations? For example: deprecations, migrations, security, or accessibility.

Best Practices Checklist

We're trying to move away from some deprecated patterns in this codebase. Please
check if your PR meets these recommendations before asking for a review:

• Any new files are using TypeScript (.ts, .tsx).
• Avoid propTypes and defaultProps in any new or modified code.
• Tests should use the helpers in src/testUtils.tsx (specifically initializeMocks)
• Do not add new fields to the Redux state/store. Use React Context to share state among multiple components.
• Use React Query to load data from REST APIs. See any apiHooks.ts in this repo for examples.
• All new i18n messages in messages.ts files have a description for translators to use.
• Avoid using ../ in import paths. To import from parent folders, use @src, e.g. import { initializeMocks } from '@src/testUtils'; instead of from '../../../../testUtils'

[openedx-webhooks]

Thanks for the pull request, @Kelketek!

This repository is currently maintained by @bradenmacdonald.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

• If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
  • This process (including the steps you'll need to take) is documented here.
• If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

• Dependencies

  This PR must be merged before / after / at the same time as ...

• Blockers

  This PR is waiting for OEP-1234 to be accepted.

• Timeline information

  This PR must be merged by XX date because ...

• Partner information

  This is for a course on edx.org.

• Supporting documentation
• Relevant Open edX discussion forum threads

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

🔘 Update the status of your PR

Your PR is currently marked as a draft. After completing the steps above, update its status by clicking "Ready for Review", or removing "WIP" from the title, as appropriate.

---

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

• Overview of Review Process for Community Contributions
• Pull Request Status Guide
• Making changes to your pull request

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

• The size and impact of the changes that it introduces
• The need for product review
• Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.

[codecov]

Codecov Report

❌ Patch coverage is 51.51515% with 48 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.36%. Comparing base (091d9a1) to head (1847a88).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/editors/containers/PdfEditor/index.tsx	44.00%	12 Missing and 2 partials ⚠️
src/editors/containers/PdfEditor/hooks.ts	0.00%	9 Missing ⚠️
src/editors/containers/PdfEditor/api.ts	0.00%	8 Missing ⚠️
src/course-unit/add-component/AddComponent.tsx	22.22%	7 Missing ⚠️
src/editors/data/redux/pdf/selectors.ts	50.00%	5 Missing ⚠️
src/editors/data/redux/thunkActions/pdf.ts	60.00%	2 Missing ⚠️
...ontainers/PdfEditor/components/PdfEditingModal.tsx	75.00%	1 Missing ⚠️
...s/containers/PdfEditor/components/UploadWidget.tsx	66.66%	1 Missing ⚠️
src/editors/data/redux/pdf/reducers.ts	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2916      +/-   ##
==========================================
- Coverage   95.51%   95.36%   -0.15%     
==========================================
  Files        1329     1340      +11     
  Lines       30544    30635      +91     
  Branches     6916     6931      +15     
==========================================
+ Hits        29173    29216      +43     
- Misses       1303     1349      +46     
- Partials       68       70       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.