build(shims): Cleanup build helpers

[grypez]

@SMotaal identified and worked around a zero-width-joiner vs combining-grapheme-joiner parsing issue in the endo bundler. For now, we have some helpers that handle the issue on the ocap-kernel side. Pending endo#2436, we should remove these helpers so that the bundle.js build script is as simple as possible, relying on endo to handle the hairy details.

[SMotaal]

Note

@endojs/endo#2436 landed and soon enough we will be dropping packages/shims/scripts/helpers/rollup-plugin-endo-script-identifier-transform.js