Add rollup import transform

[marklundin]

This PR addresses a long standing issue with the UMD build not running on devices without dynamic import() support. See #6011.

This issue stemmed from the use of dynamic import() statement, where import is a reserved keyword and would throw a SyntaxError during parsing on older browsers, even if the code path was never executed.

This PR adds a rollup transform to the UMD build only, which wraps import() statements in a dynamic function. This is only evaluated at runtime, thereby avoiding the parsing on load error. Note that this does not polyfill dynamic imports, it will simply prevent parsing errors on browser without support.

Caveats

This does put a limitation on CSP for UMD builds, however this only applies if all of the following conditions are met

1. The UMD build is used (not applicable to the ES6 build) AND
2. Hosting blocks unsafe-eval in their CSP AND
3. When using either WebGPU or importing an ESM ScriptType

I confirm I have read the contributing guidelines and signed the Contributor License Agreement.

[mvaligursky]

Looks great, but please give some time for additional opinions before merging.

@kungfooman perhaps?

[kungfooman]

Looks very good 👍