Add styles for responsive grid layout

[tellthemachines]

Trac ticket: https://core.trac.wordpress.org/ticket/64532

Adds responsive grid styles related to WordPress/gutenberg#73662 (the PHP changes were already in Gutenberg since WordPress/gutenberg#62777 as part of an experiment)
and blockGap bug fix from WordPress/gutenberg#74725

Steps for testing

Add this markup to a post:

<!-- wp:group {"align":"wide","layout":{"type":"grid","columnCount":3,"minimumColumnWidth":"117px"}} -->
<div class="wp-block-group alignwide"><!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">content</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">content</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">content</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">contente</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">content</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">contentnn</p>
<!-- /wp:paragraph -->

<!-- wp:paragraph {"backgroundColor":"accent-1"} -->
<p class="has-accent-1-background-color has-background">contnt</p>
<!-- /wp:paragraph --></div>
<!-- /wp:group -->

Save and publish. Check that the grid has 3 columns on the front end.

Go back to the editor and change min column width to be 800px. Save and go back to the front end. Switch view to mobile and check there's no horizontal scroll.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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Test this pull request with WordPress Playground.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props isabel_brison, aaronrobertshaw.

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[tellthemachines]

Columns block hashes changed due to updates this PR makes to flex layout gap calculation,

[aaronrobertshaw]

Thanks for the work on this @tellthemachines 👍

✅ This is testing as advertised
✅ Code appears consistent with the layout support and tests in Gutenberg

LGTM 🚢

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61513
GitHub commit: ea33087

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.