feat: use frontend-plugin-framework to provide a FooterSlot

[brian-smith-tcril]

• Requires fix: support frontend-platform 8.x as a peer dependency frontend-plugin-framework#60
• Requires fix: remove header and footer dependencies frontend-plugin-framework#61
• Requires feat: provide FooterSlot frontend-component-footer#423

This adds a plugin slot to provide a way to replace the footer using frontend-plugin-framework.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 56.70%. Comparing base (9693d93) to head (9c5dfae).
Report is 14 commits behind head on master.

❗ Current head 9c5dfae differs from pull request most recent head 1fa9791. Consider uploading reports for the commit 1fa9791 to get more accurate results

Files	Patch %	Lines
src/plugin-slots/FooterSlot/index.jsx	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1044      +/-   ##
==========================================
+ Coverage   56.55%   56.70%   +0.14%     
==========================================
  Files         117      120       +3     
  Lines        2456     2499      +43     
  Branches      654      673      +19     
==========================================
+ Hits         1389     1417      +28     
- Misses        996     1008      +12     
- Partials       71       74       +3     

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[arbrandes]

I know this is still a draft, but for what it's worth, I think this is the way to go. No objections!

[arbrandes]

We missed the Redwood cutoff but exactly 60 seconds. 🤷🏼‍♂️