Export named concurrently + fix TS errors with Node16

[gustavohenke]

Fixes a bunch of issues when using concurrently

1. For require() function (from both TS and pure JS)
2. With TS + import syntax, but without ES module interop
3. With TS + import syntax, but with ES module interop
4. As an ES Module (from both TS and pure JS)

On the side, the named export concurrently is now the fully configured concurrently.
This was done to simplify the exports in the index files (most likely specific to ESM, but I've lost track of why exactly).

Will add some smoke tests in a follow up PR so that this one stays mostly focused to the core changes.

Fixes #399
Fixes #454
Closes #440

[coveralls]

coverage: 99.2% (+0.003%) from 99.197%
when pulling e160bd3 on issue-399
into 0c64306 on main.

[gustavohenke]

Bit of a bump @paescuj, might proceed without a review in a few days