Promise onDispose callback

[Aukevanoost]

Hi! I had a small naive question,

Since ctx.dispose() is a Promise, would it be possible to allow ESbuild to wait for plugins as well when disposing? The possibility to add promises to the dispose callback array would allow developers to await for all plugins to be cleaned up until proceeding.

[evanw]

This sounds reasonable. Marking as a breaking change since this could potentially hypothetically something.