build(v3): Fix watch task to detect changes in ZE API package

[t1m0thyj]

What It Does
Fixes regression of #2686 in the vNext branch after we migrated from ts-loader to esbuild-loader

Although esbuild doesn't officially support TS project references, we can trick it into supporting them by adding an exports section to ZE API package.json as suggested in evanw/esbuild#1250 (comment).

Also removes 2 Webpack plugins:

• copy-webpack-plugin - It tried to overwrite files on every incremental build which could cause file access errors on Windows. Replaced with a copy-secrets npm script that runs only on build.
• tsconfig-paths-webpack-plugin - It conflicts with the conditionNames configuration added in this PR.

How to Test

• Launch the debug task to run ZE or the FTP extension which starts a watch task in the terminal
• Make a change to source code inside the "zowe-explorer-api" package and save the file
• The watch task should automatically trigger to rebuild with code changes made to ZE API
• Set a breakpoint in a TS file in the "zowe-explorer-api" package and make sure it triggers

[traeok]

Changes LGTM, was able to debug the API after making a change. Thanks Timothy for resolving this & the Secrets SDK binary issue 😋

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
18.2% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.82%. Comparing base (4548918) to head (ae65671).

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #3023   +/-   ##
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  Coverage   92.82%   92.82%           
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  Files         107      107           
  Lines       10887    10887           
  Branches     2369     2366    -3     
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  Hits        10106    10106           
  Misses        779      779           
  Partials        2        2           

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