chore(build): switch to esbuild

[sranka]

This PR modernizes the client build system to transpile the source code with esbuild. The client build time is thus reduced to 40% of the original time with equivalent build results.

More specifically:

• it replaces rollup (with tsc compiler) with tsup (relies upon esbuild instead)
• tsup still uses tsc compiler to produce typescript definition files (index.d.ts), there is no support to do so directly with esbuild (and also swc)
• esbuild is customized in order to
  • create core's browser builds by replacing node transport with browser transport
  • gzip output js files (to keep the same results as previous rollup builds)
  • output UMD files in browser distributions, UMD is not supported by esbuild OOTB; UMD builds are still required in older build pipelines and web workers

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• yarn test completes successfully
• Commit messages are conventional

[codecov-commenter]

Codecov Report

Merging #511 (44bb05c) into master (40e62c9) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #511   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           33        33           
  Lines         1256      1256           
  Branches       302       302           
=========================================
  Hits          1256      1256           

Impacted Files	Coverage Δ
packages/core/src/util/currentTime.ts	100.00% <100.00%> (ø)

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[sranka]

All examples were tried manually as well as the built files.

[bednar]

LGTM 🍻