Add 'types' field to 'exports' for modern TypeScript/Node resolution.

[DanielRosenwasser]

TL;DR I ran the native port of TypeScript on Element. This PR helps make sure that Element can build cleanly with --moduleResolution bundler, and therefore, will build more cleanly with future versions of TypeScript.

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If you run https://arethetypeswrong.github.io/ on this package, you'll get something like the following:

	"@vector-im/matrix-wysiwyg"
node10	✅
node16 (from CJS)	❌ No types
node16 (from ESM)	❌ No types
bundler	❌ No types

While this package works:

• at runtime for ESM consumers in modern versions of Node.js, and
• at check time for TypeScript users who are using old resolution modes like --moduleResolution node (a.k.a. node10)

unfortunately, it will not correctly find the .d.ts file for projects that use modern Node.js resolution (e.g. --moduleResolution NodeNext or --moduleResolution Bundler). This matters because in upcoming versions of TypeScript, --module node10 will be deprecated. So projects like Element will have a build error.

This fix should fix the last two rows, though I believe things will still be off if consuming files from CJS (due to this issue). To fix that, you'll probably need slightly more involved change with a .d.cts file or something.

Note

You can run AreTheTypesWrong locally with the CLI.

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