cts, mts, cjs, mjs, etc extension support

[weswigham]

You should probably look over weswigham#67 instead of this, so you're not reviewing two PRs of changes together - this PR is just here to run typescript bot commands on the PR~

[weswigham]

@typescript-bot pack this

[typescript-bot]

Heya @weswigham, I've started to run the tarball bundle task on this PR at 15e1904. You can monitor the build here.

[typescript-bot]

Hey @weswigham, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/109884/artifacts?artifactName=tgz&fileId=CA6E00C1F7FBD4FFDF9CEB8AEED4FBD92607027D424B717DD64E8E2DFDF9BE9902&fileName=/typescript-4.5.0-insiders.20210907.tgz"
    }
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@4.5.0-pr-45774-2".;

[weswigham]

Merged in #45884