fix: Creates CJS type declarations for CJS export.

[nzakas]

Added an additional tsconfig file that just outputs a CJS version of the .d.ts file to accompany the CJS version of the module.

fixes #136

[nzakas]

@boneskull what do you think of this approach to generating types for the CommonJS entrypoint?

[boneskull]

OK, I think this is fine.

I wonder if there is a rollup-adjacent tool that'd help w/ shipping dual-module-system packages.

I use tshy for this, which just uses tsc instead of a bundler. It also provides an escape-hatch for ES-specific stuff (e.g., import.meta).

[boneskull]

lgtm

[boneskull]

@nzakas You know, I think we can just copy dist/env.d.ts to dist/env.d.cts and it should work. I don't think we need to run tsc again.

[boneskull]

relevant: https://devblogs.microsoft.com/typescript/announcing-typescript-5-5-beta/#respecting-file-extensions-and-packagejson-in-other-module-modes