Various Download fixes

[Al12rs]

This PR addresses some of the issues identified from QA testing the download process:

• Pausing/Resuming issues
• Progress/Throughput incorrectness
• Multi selection for toolbar buttons
• Update UI when downloads are added/removed or their state changes
• Many styling fixes/adjustments.

In more details:

• fix Spine Download Button isn't showing fancy progress version while download is in progress #833
• fix Pausing a download seems to directly cancel it (it disappears from the UI). #836
• fix Resuming a download after pausing resumes from 0% #842
• fix Resuming a download after closing App resumes from 0% #843
• fix Download throughput calculation in wrong when resuming a download #844
• fix Download Time Remaining is continues counting when downloads are paused #845
• fix Update Download Progress bar styles to match figma #846
• fix Hide progress bar and numbers when no downloads are active. #847
• fix Update download "In Progress (0)" title text and color when download status changes #848
• fix Fix missing accent colors to Text in Downloads view #849
• fix Add glow effect to Spine download button #850
• fix Make download toolbar buttons work with multi selection #851
• fix Add Resume Selected and Resume All buttons to Download view #852
• Added a couple of tests for some of the functionality fixed.
• Removed UpdateOverlay test that opened the App GitHub releases page when executed.

[erri120]

I've left comments on things to change.

[Al12rs]

I've left comments on things to change.

I'm going through fixing them. Thanks for going into details, I really appreciate all the chances for improvements.

[codecov-commenter]

Codecov Report

Attention: 101 lines in your changes are missing coverage. Please review.

Comparison is base (61089f3) 0.00% compared to head (9cb0ad8) 60.37%.
Report is 2 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff            @@
##           main     #857       +/-   ##
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+ Coverage      0   60.37%   +60.37%     
=========================================
  Files         0      592      +592     
  Lines         0    18359    +18359     
  Branches      0     1424     +1424     
=========================================
+ Hits          0    11084    +11084     
- Misses        0     6939     +6939     
- Partials      0      336      +336     

Flag	Coverage Δ
Linux	59.68% <69.49%> (?)
Windows	59.60% <71.46%> (?)
clean_environment_tests	60.36% <71.46%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...ds.Networking.HttpDownloader/DTOs/DownloadState.cs	100.00% <100.00%> (ø)
...e/Buttons/Download/SpineDownloadButtonViewModel.cs	100.00% <100.00%> (ø)
src/NexusMods.App.UI/Helpers/StringFormatters.cs	87.50% <100.00%> (ø)
...rc/NexusMods.App.UI/Overlays/IOverlayController.cs	44.44% <ø> (ø)
...ightContent/Downloads/InProgressDesignViewModel.cs	100.00% <100.00%> (ø)
...exusFluentDark/Styles/Controls/Border/Toolbar.xaml	97.50% <100.00%> (ø)
...exusMods.Networking.Downloaders/DownloadService.cs	86.36% <94.44%> (ø)
src/NexusMods.App.UI/Overlays/OverlayController.cs	84.78% <0.00%> (ø)
.../NexusMods.DataModel/Activities/ActivityMonitor.cs	93.10% <0.00%> (ø)
...etworking.HttpDownloader/AdvancedHttpDownloader.cs	78.65% <90.90%> (ø)
... and 7 more

... and 575 files with indirect coverage changes