feat(workspaces): preserve d.(c|m)ts directory structure

[jacob-alford]

I ran into an issue with TypeScript in a workspace / composite TSconfig settting where TS needed the root-directory specified. This meant that all emitted declaration files were emitted with a preserved structure, i.e. inside of the source directory. This cleaned up the output quite substantially, where dist files contain plain javascript, and dts and ts files from src are colocated in the dist/src directory.

Note for library authors:

This will not produce any breaking changes with your library unless you're incidentally doing some post-processing after the fact, but note the caveat below.

If you publish from dist upgrading to 0.5.0 there is nothing you need to do. If you publish from . you will need to adjust your type exports to point to ./dist/src/... instead.