Compress CSS and JS with gzip before serving to reduce load time/page weight

[iansltx]

For #24732.

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information.
• A detailed QA plan exists on the associated ticket (if it isn't there, work with the product group's QA engineer to add it)
• Manual QA for all new/changed functionality

[ksykulev]

Seems reasonable to me.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 63.58%. Comparing base (41e8324) to head (6e74b01).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
server/service/frontend.go	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25658      +/-   ##
==========================================
- Coverage   63.59%   63.58%   -0.02%     
==========================================
  Files        1622     1622              
  Lines      155115   155122       +7     
  Branches     4055     4055              
==========================================
- Hits        98648    98636      -12     
- Misses      48696    48712      +16     
- Partials     7771     7774       +3     

Flag	Coverage Δ
backend	64.44% <0.00%> (-0.02%)	⬇️

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