chore: build plugins in esm format

[alicialics]

The basics

• I validated my changes

The details

Resolves

Fixes #1877

Proposed Changes

Build index.esm.js in blockly-scripts build

Produces additional files in /dist/

-rw-r--r--  1    8149 Sep 26 23:25 index.esm.js
-rw-r--r--  1   27721 Sep 26 23:25 index.esm.js.map

module field in plugins should be updated to this new file in the future.
This change is non-breaking unless a user includes non-browser (ie node) code, as this was the case for dev-tools repo where it had mocha/sinon code that are being exported..

Reason for Changes

Test Coverage

Tested vite build for plugin-workspace-search. See #1877 for discussion.

Documentation

Additional Information

cc @cpcallen @maribethb

[conventional-commit-lint-gcf]

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[maribethb]

Hey Zoey, thanks for opening this PR. It kicked off some discussion in the team, but at this time we don't want to introduce a new build tool into our pipeline. It did bring up an interesting idea that we could run webpack twice, one to output esm and one to continue to output minified umd, to meet this need. However this idea still needs more discussion within the team. I'm going to close this PR now, but we do appreciate your thoughts in this space! Thanks!