Allow workers to load CJS plugins

[garrettjstevens]

Fixes #3785

Worked on this with @cmdcolin during our pairing yesterday, and since then I've created a CJS plugin to test with that does node-native module import on the worker.

Because our electron version now uses node 18, we can use fetch natively. Also because webpack 5 doesn't do any polyfilling, we can avoid a bunch of window.requires that were a workaround to avoid the polyfilling.

[codecov]

Codecov Report

Merging #3796 (a9e2283) into main (8a3ac2d) will increase coverage by 0.22%.
The diff coverage is 8.10%.

❗ Current head a9e2283 differs from pull request most recent head da83d0e. Consider uploading reports for the commit da83d0e to get more accurate results

@@            Coverage Diff             @@
##             main    #3796      +/-   ##
==========================================
+ Coverage   64.24%   64.47%   +0.22%     
==========================================
  Files         987      990       +3     
  Lines       29671    29574      -97     
  Branches     7096     7094       -2     
==========================================
+ Hits        19063    19068       +5     
+ Misses      10444    10341     -103     
- Partials      164      165       +1     

Impacted Files	Coverage Δ
packages/core/rpc/WebWorkerRpcDriver.ts	0.00% <ø> (ø)
packages/product-core/src/rpcWorker.ts	0.00% <0.00%> (ø)
...browse-desktop/src/components/StartScreen/util.tsx	0.00% <0.00%> (ø)
products/jbrowse-desktop/src/rootModel/index.ts	47.05% <ø> (ø)
products/jbrowse-desktop/src/rpcWorker.ts	0.00% <0.00%> (ø)
...ucts/jbrowse-desktop/src/sessionModel/TrackMenu.ts	8.57% <0.00%> (ø)
products/jbrowse-desktop/src/util.tsx	0.00% <0.00%> (ø)
products/jbrowse-react-app/src/rpcWorker.ts	0.00% <0.00%> (ø)
.../jbrowse-react-linear-genome-view/src/rpcWorker.ts	0.00% <0.00%> (ø)
products/jbrowse-web/src/rpcWorker.ts	0.00% <0.00%> (ø)
... and 2 more

... and 2 files with indirect coverage changes

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