Fix double-extension on file download

[danburonline]

Fixes #4529

Description

Before, when you downloaded a single file via the interface, let's say example.json, the download window would show example.json.json, which is incorrect. With this change, this won't happen again.

How has this been tested?

• Locally with dev and prod builds and manual uploading files with extensions, with no extensions and double extensions, such as example.json.json.
• Added unit tests for several test cases.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have added necessary unit and integration tests.
• I have added screenshots (if applicable), in the comment section.

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (22ca26d) 48.00% compared to head (de04188) 48.08%.
Report is 1 commits behind head on develop.

Files	Patch %	Lines
src/shared/containers/ResourceActionsContainer.tsx	0.00%	2 Missing ⚠️
src/shared/utils/download.ts	87.50%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1439      +/-   ##
===========================================
+ Coverage    48.00%   48.08%   +0.07%     
===========================================
  Files          249      249              
  Lines        11365    11368       +3     
  Branches      2655     2655              
===========================================
+ Hits          5456     5466      +10     
+ Misses        5876     5869       -7     
  Partials        33       33              

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[bilalesi]

good job, small comment for covering corner case