fix(deno): Add prepack for deno build

[AbhiPrasad]

fixes #12698

Adds back prepack script just for deno which was removed in #12656 because it's a breaking change for the deno package which relies on the directory structure for their import path.

[mydea]

Could we actually put a minimal prepack script in here, that does not have all the variables etc. but really does only the things we specifically need for deno? Otherwise it will be harder in the future to understand what of this is actually needed for deno to work etc.?

FWIW I'm also OK with merging this as-is and streamlining it in a follow up, if we want to get this out ASAP.

[AbhiPrasad]

Could we actually put a minimal prepack script in here, that does not have all the variables etc. but really does only the things we specifically need for deno? Otherwise it will be harder in the future to understand what of this is actually needed for deno to work etc.?

Done with 17c1a4d - also experimented with jsdoc types (because I didn't want to refactor the require calls), so was an interesting experiment overall.

[mydea]

nice! 🚀