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.
# Pyodide packages

This folder contains the list of packages built in pyodide.

There are two categories of packages,
 1. Those that contain a `meta.yaml` are built with the Python build system
    using `pyodide_build/buildall.py` and `pyodide_build/buildpkg.py` scripts.
 2. Those that contain a `Makefile` are build from the main `Makefile` in the
    root folder.

Packages of the second category will be migrated to use a `meta.yaml` in the
future (see [#713](https://github.com/pyodide/pyodide/issues/713)).

# Pyodide packages

This folder contains the list of packages built in pyodide.

There are two categories of packages,
 1. Those that contain a `meta.yaml` are built with the Python build system
    using `pyodide_build/buildall.py` and `pyodide_build/buildpkg.py` scripts.
 2. Those that contain a `Makefile` are build from the main `Makefile` in the
    root folder.

Packages of the second category will be migrated to use a `meta.yaml` in the
future (see [#713](https://github.com/pyodide/pyodide/issues/713)).
