Added excerpt panel to document inspector

[mariano-formidable]

Summary

This PR adds the Excerpt Panel to the document inspector. It also adds a TextArea Storybook sample and ExcerptPanel tests.

Relevant Technical Choices

The figma design displays a 100 character limit, but I choose to up it to 200 characters based on Pascal's suggestion (it follows how Twitter does it) in the main ticket (#490).

User-facing changes

The "Excerpt Panel" will now appear within the "Document" tab for the entire story (above the "Permalink Panel").

Testing Instructions

1.) Open up a new or existing story in the Editor.
2.) Click on "Document" in the panel to the right to revel the document inspector.
3.) Scroll down the document inspector to find the "Excerpt" panel. It should be located below "Publishing" and above "Permalink".
4.) In the Excerpt panel you should be able to do the following:

• Type up a small excerpt. Click save. Refresh the page and notice that the excerpt remains (meanings it was saved off with the story).
• You should be able to remove the excerpt and save with an empty excerpt.
• Type in or copy-n-paste a message over 200 characters and it should be auto-truncated to 200 chars.

Fixes #490

Screenshots

Empty Excerpt panel:

Nicely filled Excerpt panel:

[github-actions]

Size Change: +765 B (0%)

Total Size: 1.23 MB

Filename	Size	Change
assets/js/edit-story.js	490 kB	+471 B (0%)
assets/js/stories-dashboard.js	576 kB	+294 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
assets/css/edit-story.css	268 B	0 B
assets/css/stories-dashboard.css	305 B	0 B
assets/css/web-stories-embed-block.css	515 B	0 B
assets/js/chunk-web-stories-template-0-********************.js	10.2 kB	0 B
assets/js/chunk-web-stories-template-1-********************.js	10.3 kB	0 B
assets/js/chunk-web-stories-template-2-********************.js	10 kB	0 B
assets/js/chunk-web-stories-template-3-********************.js	10.5 kB	0 B
assets/js/chunk-web-stories-template-4-********************.js	10.6 kB	0 B
assets/js/chunk-web-stories-template-5-********************.js	6.86 kB	0 B
assets/js/chunk-web-stories-template-6-********************.js	9.91 kB	0 B
assets/js/chunk-web-stories-template-7-********************.js	9.78 kB	0 B
assets/js/web-stories-activation-notice.js	63.6 kB	0 B
assets/js/web-stories-embed-block.js	16.9 kB	0 B

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[codecov]

Codecov Report

Merging #4264 into main will decrease coverage by 0.13%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##             main    #4264      +/-   ##
==========================================
- Coverage   83.35%   83.22%   -0.14%     
==========================================
  Files         831      834       +3     
  Lines       14535    14659     +124     
==========================================
+ Hits        12116    12200      +84     
- Misses       2419     2459      +40     

Flag	Coverage Δ
#karmatests	71.28% <77.77%> (-0.14%)	⬇️
#unittests	66.00% <88.88%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...components/inspector/document/documentInspector.js	100.00% <ø> (ø)
assets/src/edit-story/components/form/textArea.js	86.66% <86.66%> (ø)
...dit-story/components/inspector/document/excerpt.js	100.00% <100.00%> (ø)
assets/src/dashboard/theme.js	83.33% <0.00%> (ø)
...s/src/dashboard/app/views/templateDetails/index.js	96.36% <0.00%> (ø)
...src/dashboard/components/cardGallery/components.js	100.00% <0.00%> (ø)
assets/src/dashboard/utils/useGridViewKeys.js	29.68% <0.00%> (ø)
...sets/src/dashboard/components/cardGallery/index.js	96.49% <0.00%> (+1.36%)	⬆️
... and 3 more

[barklund]

Works as expected and looks great - just two minor comments about simplifications.

[dmmulroy]

Had two small nits but this looks great and works well 👍

[BrittanyIRL]

Text area works as you've laid out in the editor both with cursor and keyboard. Storybook add is great, thank you for doing that! And unit tests are working locally for me.