Packages the distutils stdlib module as a standalone package,
```
377K distutils.data
221K distutils.data.br
19K distutils.js
```
to reduce the minimal pyodide size.

Part of #1542 

This also,
 - adds documentation on what's supported or not in the stdlib
 - makes a few changes to `pyodide_build/buildall.py` to be able to add such stdlib packages as a dependency in other packages (which didn't work before). For instance, until there is a release with https://github.com/pypa/packaging/pull/396 micropip has a dependency on distutils.
Unvendor distutils. Packages the distutils stdlib module as a standalone package,
```
377K distutils.data
221K distutils.data.br
19K distutils.js
```
to reduce the minimal pyodide size.

Part of #1542 

This also,
 - adds documentation on what's supported or not in the stdlib
 - makes a few changes to `pyodide_build/buildall.py` to be able to add such stdlib packages as a dependency in other packages (which didn't work before). For instance, until there is a release with https://github.com/pypa/packaging/pull/396 micropip has a dependency on distutils.
package:
  name: kiwisolver
  version: 1.3.1
source:
  sha256: 950a199911a8d94683a6b10321f9345d5a3a8433ec58b217ace979e18f16e248
  url: https://files.pythonhosted.org/packages/90/55/399ab9f2e171047d28933ae4b686d9382d17e6c09a01bead4a6f6b5038f4/kiwisolver-1.3.1.tar.gz
test:
  imports:
  - kiwisolver

package:
  name: kiwisolver
  version: 1.3.1
source:
  sha256: 950a199911a8d94683a6b10321f9345d5a3a8433ec58b217ace979e18f16e248
  url: https://files.pythonhosted.org/packages/90/55/399ab9f2e171047d28933ae4b686d9382d17e6c09a01bead4a6f6b5038f4/kiwisolver-1.3.1.tar.gz
test:
  imports:
  - kiwisolver
