Enable XO on new file extensions: cts and mts

[fregante]

https://devblogs.microsoft.com/typescript/announcing-typescript-4-5-beta/#new-file-extensions

I know, I know. But…

[thetutlage]

Can this rule also check for missing file extensions and dis-allow that? Since, a local import must have a .js file extension it must be nice to error out when the extension is missing all together.

Not sure how tricky the rule will be, as it will have to ignore packages

[fregante]

This request is not about rules but the actual support of the extensions in XO, which instead currently ignores these files.

If you have an idea for a rule you might want to check out eslint-plugin-import