feat(typescript): add transformers factory

[Haringat]

Rollup Plugin Name: typescript

This PR contains:

• [ ] bugfix
• [x] feature
• [x] refactor
• [x] documentation
• [ ] other

Are tests included?

• [x] yes (bugfixes and features will not be merged without tests)
• [ ] no

Breaking Changes?

• [ ] yes (breaking changes will not be merged unless absolutely necessary)
• [x] no

If yes, then include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

resolves #1667

Description

This allows creating custom transformers in the typescript plugin together ahead-of-time in a factory function. This allows for shorter rollup configs in certain cases and enables using similar factory-style transformers like the angular compiler API.

This also cleans up a few places minor internals in the typescript plugin (missing parameter descriptions, deprecated APIs, generic identifiers)

[Haringat]

@shellscape Would you mind reviewing this?

[shellscape]

@Haringat I'm backed up at work. will be end of the week before I circle back to open source.

[Haringat]

@shellscape what calendar are we going with?

[shellscape]

I'm using the Julian calendar.