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.
*.a
*.o
*.pyc

*.egg-info/

__pycache__

.docker_home
.hypothesis
.idea
.mozilla
.mypy_cache/
.pytest_cache/
.vscode

build
ccache
cpython/downloads
cpython/installs
docs/_build/
emsdk/emsdk
geckodriver.log
node_modules/
packages/.artifacts
packages/*/build.log

*.a
*.o
*.pyc

*.egg-info/

__pycache__

.docker_home
.hypothesis
.idea
.mozilla
.mypy_cache/
.pytest_cache/
.vscode

build
ccache
cpython/downloads
cpython/installs
docs/_build/
emsdk/emsdk
geckodriver.log
node_modules/
packages/.artifacts
packages/*/build.log
