Add experimental video download support

[thornbill]

Settings Screen	New Download	Download Complete	Edit Downloads	Delete Confirmation

This will definitely require some follow-up work, but I didn't want this PR to get any bigger.

Follow-up work is covered by #372

Fixes #22

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
4 Code Smells

No Coverage information
0.0% Duplication

[codecov[bot]]

Codecov Report

Merging #366 (ab2159f) into master (38b6a93) will decrease coverage by 1.24%. The diff coverage is 54.24%.

@@            Coverage Diff             @@
##           master     #366      +/-   ##
==========================================
- Coverage   61.84%   60.60%   -1.25%     
==========================================
  Files          41       46       +5     
  Lines         781      929     +148     
  Branches      162      186      +24     
==========================================
+ Hits          483      563      +80     
- Misses        270      333      +63     
- Partials       28       33       +5     

Impacted Files	Coverage Δ
App.js	0.00% <0.00%> (ø)
components/NativeShellWebView.js	15.38% <0.00%> (-1.29%)	:arrow_down:
navigation/TabNavigator.js	0.00% <0.00%> (ø)
screens/DevSettingsScreen.js	45.45% <0.00%> (-17.05%)	:arrow_down:
screens/DownloadScreen.js	35.84% <35.84%> (ø)
screens/HomeScreen.js	55.88% <66.66%> (+0.65%)	:arrow_up:
components/DownloadListItem.js	100.00% <100.00%> (ø)
models/DownloadModel.ts	100.00% <100.00%> (ø)
stores/DownloadStore.ts	100.00% <100.00%> (ø)
stores/MediaStore.js	100.00% <100.00%> (ø)
... and 3 more

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[pinkworld123]

please allow music and audio books download also. thanks