Replace shortid with vendored nanoid

[cmdcolin]

Shortid warns that it is deprecated on install https://www.npmjs.com/package/shortid

This PR switches shortid to nanoid

In order to do so, the codebase of nanoid is vendored (copied) into @jbrowse/core/util/nanoid because installing it from NPM gives tricky to solve issues with pure-ESM especially with jest

These could be worked around in jest probably but vendoring solves 'automatically' for us

xref ai/nanoid#439

[codecov]

Codecov Report

Merging #3855 (192b8e4) into main (6f1fa62) will increase coverage by 0.01%.
Report is 11 commits behind head on main.
The diff coverage is 64.00%.

@@            Coverage Diff             @@
##             main    #3855      +/-   ##
==========================================
+ Coverage   64.39%   64.41%   +0.01%     
==========================================
  Files         999     1003       +4     
  Lines       29710    29743      +33     
  Branches     7125     7134       +9     
==========================================
+ Hits        19133    19158      +25     
- Misses      10415    10420       +5     
- Partials      162      165       +3     

Files Changed	Coverage Δ
packages/app-core/src/JBrowseConfig/index.ts	100.00% <ø> (ø)
packages/core/rpc/WebWorkerRpcDriver.ts	0.00% <0.00%> (ø)
packages/product-core/src/Session/BaseSession.ts	72.41% <ø> (ø)
...ckSelectorWidget/components/tree/HamburgerMenu.tsx	31.34% <0.00%> (ø)
...r-genome-view/src/createModel/createConfigModel.ts	77.77% <ø> (ø)
...r-genome-view/src/createModel/createConfigModel.ts	55.55% <ø> (ø)
...jbrowse-web/src/components/ConfigWarningDialog.tsx	0.00% <0.00%> (ø)
...browse-web/src/components/SessionWarningDialog.tsx	35.71% <0.00%> (ø)
products/jbrowse-web/src/SessionLoader.ts	70.68% <50.00%> (ø)
packages/core/util/nanoid.js	59.25% <59.25%> (ø)
... and 9 more

... and 1 file with indirect coverage changes

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