Support .mts, .cts, .d.mts, and .d.cts

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Much like .mjs and .cjs use the .ts icon, .mts and .cts should use the .ts icon.

Similar logic applies to .d.mts and .d.cts.

Here's the typescript docs:

Node.js supports two extensions to help with this: .mjs and .cjs. .mjs files are always ES modules, and .cjs files are always CommonJS modules, and there’s no way to override these.

In turn, TypeScript supports two new source file extensions: .mts and .cts. When TypeScript emits these to JavaScript files, it will emit them to .mjs and .cjs respectively.

Furthermore, TypeScript also supports two new declaration file extensions: .d.mts and .d.cts. When TypeScript generates declaration files for .mts and .cts, their corresponding extensions will be .d.mts and .d.cts.