Fix overwriting broken symlink with --force in add-track CLI

[cmdcolin]

This unconditionally performs an fs.unlink when using force so that it doesn't run into the issue with broken symlinks, mentioned in #2768 (comment)

[codecov]

Codecov Report

Merging #2774 (82d86be) into main (eb7cfb7) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2774   +/-   ##
=======================================
  Coverage   60.16%   60.16%           
=======================================
  Files         572      572           
  Lines       26615    26614    -1     
  Branches     6487     6487           
=======================================
  Hits        16012    16012           
+ Misses      10278    10277    -1     
  Partials      325      325           

Impacted Files	Coverage Δ
products/jbrowse-cli/src/commands/add-track.ts	63.38% <100.00%> (-0.18%)	⬇️
products/jbrowse-web/src/util.ts	27.27% <0.00%> (ø)
packages/core/util/analytics.ts	91.83% <0.00%> (+2.04%)	⬆️

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