fix: support .mts and .cts out of the box

[RebeccaStevens]

Rollup Plugin Name: typescript

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

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

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• 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:

Description

Currently out of the box the typescript plugin only supports .ts and .tsx extensions. This PR adds support for .mts and .cts as well without the user needing to modify the includes option.

Additionally only .d.ts were supported as type declaration files, this PR also adds support for .d.mts and .d.cts files.

[perrin4869]

For what it's worth, I think #1194 already adds support for this?

[RebeccaStevens]

Yeah, that's true. It would be good if we can get one of these merged soon as currently libraries using the .d.mts extension cannot be used in rollup build environment.

[perrin4869]

I think #1194 is more complete and merging this one will only make it harder to resolve conflicts
@NotWoods any chance you can review that PR?
I can resolve the new conflicts but i don't want to keep resolving conflicts indefinitely...

[shellscape]

Thanks for the work on this PR. #1194 supersedes this PR and we've just merged that.