feat(js): add browser config

[wolfv]

This adds a "iife" config so that we can load the JS file and access rattler through window.Rattler ....

It works for my usecase in Retool, although I am not totally sure if there is another way with the modules we have already.

[baszalmstra]

Cant the normal esm build just be in that format?

@trim21 Thoughts?

[trim21]

Cant the normal esm build just be in that format?

@trim21 Thoughts?

Although I would prefer downstream projects use a bundler to pack them, but it's not a bad idea to add this, I don't have strong opinion on this.

[wolfv]

Any idea why the tests are failing here? I triggered them on main and that doesn't show the same failure (#1249).

Is jest trying to use the browser files for some reason? Should we put them in a different folder? Like dist-browser? So that jest doesn't discover them?

[trim21]

run build-cjs after run build-wasm should fix it, or add this output in rollup.config.esm.js would also fix it

we should consider fix this building
order bug in other pr, merging rollup config files or maybe dropping cjs since nodejs support loading esm in cjs in all lts version