Beta: Export beta ContentPreview component

[jeremywiebe]

Summary:

Export ContentPreview component for CP to start adopting in the v2 exercise editor.

Issue: "none"

Test plan:

none

[github-actions]

npm Snapshot: Published

Good news!! We've packaged up the latest commit from this PR (61501c5) and published it to npm. You
can install it using the tag PR1627.

Example:

yarn add @khanacademy/perseus@PR1627

If you are working in Khan Academy's webapp, you can run:

./dev/tools/bump_perseus_version.sh -t PR1627

[github-actions]

Size Change: +630 B (+0.07%)

Total Size: 861 kB

Filename	Size	Change
packages/perseus-editor/dist/es/index.js	278 kB	+630 B (+0.23%)

ℹ️ View Unchanged

Filename	Size
packages/kas/dist/es/index.js	38.3 kB
packages/keypad-context/dist/es/index.js	760 B
packages/kmath/dist/es/index.js	4.27 kB
packages/math-input/dist/es/index.js	78 kB
packages/math-input/dist/es/strings.js	1.79 kB
packages/perseus-core/dist/es/index.js	1.48 kB
packages/perseus-linter/dist/es/index.js	22.2 kB
packages/perseus/dist/es/index.js	417 kB
packages/perseus/dist/es/strings.js	3.36 kB
packages/pure-markdown/dist/es/index.js	3.66 kB
packages/simple-markdown/dist/es/index.js	12.4 kB

_{compressed-size-action}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.33%. Comparing base (12b8e01) to head (61501c5).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1627      +/-   ##
==========================================
- Coverage   70.35%   70.33%   -0.02%     
==========================================
  Files         549      574      +25     
  Lines      107191   111719    +4528     
  Branches     7777    11791    +4014     
==========================================
+ Hits        75410    78575    +3165     
- Misses      31594    33144    +1550     
+ Partials      187        0     -187     

see 1123 files with indirect coverage changes

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