Fix ability to search and load data files using lower case refName aliases

[cmdcolin]

Currently, you can query for lower case ref names such as e.g. ctga:1-100 on volvox, but with refnamealiases it does not work. E.g. contiga:1-100 fails

This fixes it so that you can use lower case naming in the refname autocomplete for searching

Small amount of other refactoring code in PR, and adding chrMT to hg19 refname aliases

[cmdcolin]

Fixes #3039

[codecov]

Codecov Report

Merging #3041 (8d1f8a0) into main (08c8111) will increase coverage by 0.08%.
The diff coverage is 91.42%.

@@            Coverage Diff             @@
##             main    #3041      +/-   ##
==========================================
+ Coverage   61.70%   61.78%   +0.08%     
==========================================
  Files         590      590              
  Lines       26915    26912       -3     
  Branches     6526     6525       -1     
==========================================
+ Hits        16607    16627      +20     
+ Misses      10005     9982      -23     
  Partials      303      303              

Impacted Files	Coverage Δ
...inearGenomeView/components/SearchResultsDialog.tsx	71.69% <ø> (+22.64%)	⬆️
...view/src/LinearGenomeView/components/SearchBox.tsx	86.84% <50.00%> (-0.40%)	⬇️
packages/core/assemblyManager/assemblyManager.ts	71.62% <87.50%> (ø)
...enome-view/src/LinearGenomeView/components/util.ts	85.71% <90.00%> (+10.71%)	⬆️
packages/core/assemblyManager/assembly.ts	92.25% <100.00%> (+0.88%)	⬆️
...fig/src/RefNameAliasAdapter/RefNameAliasAdapter.ts	92.30% <100.00%> (ø)
...iew/src/LinearGenomeView/components/ImportForm.tsx	78.37% <100.00%> (+0.60%)	⬆️
.../linear-genome-view/src/LinearGenomeView/index.tsx	84.61% <0.00%> (-0.34%)	⬇️
products/jbrowse-web/src/util.ts	27.27% <0.00%> (ø)
products/jbrowse-cli/src/commands/text-index.ts	70.62% <0.00%> (+1.39%)	⬆️
... and 5 more

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[cmdcolin]

this doesn't support queries like chrmt:1-100, but it could be a starter

[cmdcolin]

allows lowercase locstrings now, and also allows data files with either Chr1 or chr1. various tests added also to try to cover these cases, with a bit of refactoring to help the import form's search box to use the same fetchResults utility as the lgv header search box