Print trailing comma for type parameters

[sosukesuzuki]

Description

Fixes #3662.

I think we can do this at next major.

Checklist

• I’ve added tests to confirm my change works.
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨

[thorn0]

TS 2.7 was released 3 years ago. I don't think we need a major version for this.

[thorn0]

This logic relies on the file extension (isTSXFile), so I can't reproduce this on the playground:

test-tsx.tsx:

const f = <Tttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt, >() => 1

$ prettier test-tsx.tsx --trailing-comma all
const f = <
  Tttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt,,
>() => 1;

See also #3662 (comment)

BTW, this also means that Prettier has been outputting code with trailing commas in type parameters for a while already, at least for TSX. so this change is definitely safe for a non-major version.