feat(web): add headings, blockquotes and codeblocks

[pkaramon]

Summary

• added <h1> to <h6>, <blockquote> and <codeblock> to web
• added handling of htmlStyle for new elements
• added visual regression tests for new elements
• added tests for custom keyboard navigation, merging adjacent blocks etc. behavior that was added to match tiptap to the native implemenation
• moved StrictMarksPlugin to pmPlugins (ProseMirror plugins), a directory that contains a lot of the custom logic to match tiptap to native
• VisualRegression screen now displays the current html and also allows customizing htmlStyle during a test
• removed padding from inline code, as the native does not have it, and it also caused issues with headings, where the padding intruded on elements below.

Test Plan

• Run yarn test:e2e:web to see if all the new web tests pass
• Run yarn example-web dev and play around with new elements

Screenshots / Videos

Compatibility

OS	Implemented
iOS	❌
Android	❌
Web	✅

Checklist

• E2E tests are passing
• Required E2E tests have been added (if applicable)