TypeScript: General JSX types export for jsx-runtime, fixes TS4.1 compatibility

[ddprrt]

This is Re: microsoft/TypeScript#41330 - @weswigham's Pull Request makes sure to pick up the right types when using the new JSX transforms, looking for a general JSX namespace export. This also gets rid of the JSX namespace exports within each factory.

However, what I've seen is that TypeScript compiles to the React "convention" for jsx-runtime, which is with a configuration like that:

{
  "compilerOptions": {
    ...
    "jsx": "react-jsx", 
    "jsxImportSource": "preact",
  }
}

The imports become e.g.

var jsx_runtime_js_1 = require("preact/jsx-runtime.js");

I think setting the configuration to

{
  "compilerOptions": {
    ...
    "jsx": "react-jsx", 
    "jsxImportSource": "preact/compat",
  }
}

should do the trick with #2805 being merged. This would require another jsx-dev-runtime.js in compat to make it fully compatible with all compiler options.

[coveralls]

Coverage remained the same at 100.0% when pulling 9204b0a on ddprrt:master into 415a5ca on preactjs:master.

[marvinhagemeister]

Sweet, thank you for the PR 🙌