Eject react-script config from jbrowse-web and jbrowse-desktop

[cmdcolin]

This is a less heavy handed approach to #3852

We can try to reduce amount of config over time, but that PR aggressively tried to prune the amount of webpack config. This PR is comparatively more similar to "just running react-scripts eject" and keeping the result

[codecov]

Codecov Report

Merging #3885 (8185afd) into main (a3196fa) will decrease coverage by 0.04%.
Report is 3 commits behind head on main.
The diff coverage is 58.00%.

@@            Coverage Diff             @@
##             main    #3885      +/-   ##
==========================================
- Coverage   64.45%   64.42%   -0.04%     
==========================================
  Files        1004     1004              
  Lines       29809    29789      -20     
  Branches     7154     7143      -11     
==========================================
- Hits        19214    19191      -23     
- Misses      10429    10432       +3     
  Partials      166      166              

Files Changed	Coverage Δ
packages/app-core/src/ui/App/App.tsx	96.55% <ø> (ø)
packages/app-core/src/ui/App/ViewMenu.tsx	78.57% <ø> (ø)
...BaseFeatureWidget/BaseFeatureDetail/Attributes.tsx	96.55% <ø> (ø)
...eWidget/SequenceFeatureDetails/ProteinSequence.tsx	100.00% <ø> (ø)
packages/core/BaseFeatureWidget/util.tsx	73.68% <ø> (ø)
packages/core/TextSearch/TextSearchManager.ts	97.14% <ø> (ø)
packages/core/pluggableElementTypes/AdapterType.ts	83.33% <ø> (ø)
...uggableElementTypes/models/InternetAccountModel.ts	61.17% <0.00%> (ø)
...ementTypes/renderers/ServerSideRenderedContent.tsx	0.00% <0.00%> (ø)
packages/core/rpc/RpcManager.ts	70.58% <ø> (ø)
... and 153 more

... and 2 files with indirect coverage changes

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