Add disableImportOptimizations compiler option

[ghost]

Adds new compiler option disableImportOptimizations to disable import optimizations (removal) as discussed in #9191.

[msftclas]

All CLA requirements met.

[RyanCavanaugh]

We're unable to accept PRs for Suggestions tagged In Discussion - please see the PR template. Thanks!

[ghost]

@RyanCavanaugh How about you guys provide us an adequate solution then? The issue is almost 3 years old.

[marcj]

@raphaelhittich, cool! Could you fork TypeScript and publish your version on npm?
Removing unused imports that have side-effects (like decorators on a class that registers itself in a global context) it literally one of the biggest DX breaker of TS, so I guess a lot of people would use your fork if they need such a solution. Forking is the only option if Microsoft thinks they know it better. Maybe we can fix then also the whole nominal type and runtime reflection disaster.
I can support you with time and $, if you need any help. Maybe it makes sense to create a patreon then as I think a lot of people/projects will use it since it's really a game changer.