Fix REPL base url to allow hosting it on proxy environments

[rafaelbey]

Summary

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• Test(s) added
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[changeset-bot]

🦋 Changeset detected

Latest commit: 7ba4db6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
@finos/legend-application-repl-deployment	Patch
@finos/legend-application-repl	Patch
@finos/legend-application-query-bootstrap	Patch
@finos/legend-application-studio-bootstrap	Patch
@finos/legend-application-pure-ide-deployment	Patch
@finos/legend-application-query-deployment	Patch
@finos/legend-application-studio-deployment	Patch
@finos/legend-server-showcase-deployment	Patch

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 47.96%. Comparing base (1ce2ea7) to head (7ba4db6).
Report is 88 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3169      +/-   ##
==========================================
- Coverage   48.20%   47.96%   -0.25%     
==========================================
  Files        2007     1975      -32     
  Lines      338437   335659    -2778     
  Branches    13019    12767     -252     
==========================================
- Hits       163139   160984    -2155     
+ Misses     174989   174675     -314     
+ Partials      309        0     -309     

Files	Coverage Δ
...tion-repl/src/application/LegendREPLGridClient.tsx	0.00% <0.00%> (ø)
...s/legend-application-repl-deployment/src/index.tsx	0.00% <0.00%> (ø)

... and 256 files with indirect coverage changes