Disable copy/delete menu items for reference sequence track

[teresam856]

Issue 1459
In this PR:

• disables the copy/delete menu items for the reference sequence track
• adds a check in trackConfigurations to verify that trackConfAssemblies is not undefined before checking if it includes an assembly name was already resolved on master branch
• adds test

[codecov]

Codecov Report

Merging #1689 (3ff2468) into master (16a142d) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1689      +/-   ##
==========================================
- Coverage   58.96%   58.95%   -0.01%     
==========================================
  Files         446      446              
  Lines       20434    20436       +2     
  Branches     4812     4814       +2     
==========================================
  Hits        12048    12048              
+ Misses       8091     8090       -1     
- Partials      295      298       +3     

Impacted Files	Coverage Δ
products/jbrowse-web/src/sessionModelFactory.ts	63.01% <100.00%> (+0.25%)	⬆️
...inearGenomeView/components/RefNameAutocomplete.tsx	89.36% <0.00%> (-4.26%)	⬇️
products/jbrowse-desktop/src/factoryReset.ts	0.00% <0.00%> (ø)
...y-jbrowse/src/JBrowse1Connection/jb1ConfigParse.ts	25.88% <0.00%> (ø)
...src/LinearPileupDisplay/components/FilterByTag.tsx	5.00% <0.00%> (ø)

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