Introduce Upload File endpoint

[tchaton]

What does this PR do?

This PR enables us to get rid of the File Server to upload files to the Shared Storage and reduce cost of the Training Studio Cloud App.

Furthermore, I made some tests and it seems the async mechanism enables to keep fetching the Rest API while uploading a file.

Screen.Recording.2022-09-15.at.09.50.28.mov

Fixes #<issue_number>

Does your PR introduce any breaking changes? If yes, please list them.

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[codecov]

Codecov Report

Merging #14703 (0a525b8) into master (a5b0f8b) will increase coverage by 1%.
The diff coverage is 35%.

@@            Coverage Diff            @@
##           master   #14703     +/-   ##
=========================================
+ Coverage      84%      85%     +1%     
=========================================
  Files         395      328     -67     
  Lines       28813    25804   -3009     
=========================================
- Hits        24102    21880   -2222     
+ Misses       4711     3924    -787     

[awaelchli]

Is it needed to add docs anywhere for this?

[hhsecond]

looks good. Just one question