feat: Add slots for video and file upload components and alerts

[xitij2000]

This change add plugin slots for the file and video upload components, and the alerts components on those pages.

(cherry picked from commit 9c79a41)

[codecov]

Codecov Report

Attention: Patch coverage is 95.72650% with 5 lines in your changes missing coverage. Please review.

Project coverage is 92.65%. Comparing base (acbd7fa) to head (2cd1e96).
Report is 13 commits behind head on asu-moe/redwood-css.

Files with missing lines	Patch %	Lines
src/files-and-videos/generic/EditFileErrors.jsx	69.23%	4 Missing ⚠️
src/plugin-slots/CourseVideosSlot/index.jsx	98.27%	1 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                   @@
##           asu-moe/redwood-css      #77      +/-   ##
=======================================================
+ Coverage                92.54%   92.65%   +0.10%     
=======================================================
  Files                      706      710       +4     
  Lines                    12515    12564      +49     
  Branches                  2728     2740      +12     
=======================================================
+ Hits                     11582    11641      +59     
+ Misses                     898      888      -10     
  Partials                    35       35              

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