Flag to allow global augmentation

[RoenLie]

Not allowing global augmentation has the effect of making some libraries features completely unusable. Say you have a custom element or jsx library which augments the available global jsx or html types. These are global interfaces commonly used for these purposes. Without having a way of allowing global augmentations, one would have to only publish this package to npm, creating a weird scenario where almost all packages can be deployed to jsr, while a few need a completely different publishing routine.

For reference I did attempt allowing slow types, but the publishing step still blocked publishing due to global augmentations.

[Ionaru]

Dupe of https://github.com/jsr-io/jsr/issues/339

Related to https://github.com/denoland/deno/issues/23427