Refresh: About - seperate components of "hero"

[stephaniehobson]

One-line summary

Early drafts of the manifesto page show the 3 pieces of the "hero" being re-used in different combinations. This PR pre-emptivly separates them into more independent components.

Significant changes and points to review

• separate about "hero" into 3 components (intro, feature, picto)
• add alternate white and black backgrounds
• move image from m24/about folder to mozorg/about/m24
• optimize community and manifesto images

Issue / Bugzilla link

14893

Testing

http://localhost:8000/en-US/about/ with refresh switch on

Note: this will thoroughly break the homepage if https://github.com/mozilla/bedrock/pull/15508 has not merged. That's okay. It's expected. #15508 will fix it

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.71%. Comparing base (e4df84e) to head (4037a08). Report is 11 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #15510 +/- ## ======================================= Coverage 78.71% 78.71% ======================================= Files 156 156 Lines 8197 8197 ======================================= Hits 6452 6452 Misses 1745 1745 ```

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