This change updates Matter to use Pigweed's new Python build system.
This reduces the number of pip installs performed during bootstrap and
builds to just a single pigweed package along with any others
specified in //BUILD.gn.

All python_actions performed duing a GN build do not rely on any pip
install of any in-tree python packages including Pigweed ones. Instead
build a venv is created in the out directory with only 3rd party deps
installed. All Python imports of in-tree packages are accomplished by
setting PYTHONPATH for each python_action. This allows scaling up the
number of in-tree Python packages without a significant impact to
build speed.

Bootstrap time is slightly reduced however all Pigweed Python modules
are installed allong with the Python packages from:
- //examples/common/pigweed/rpc_console
- //examples/chef
- //integrations/mobly

Before:
```
  Setting up Python environment.....done (1m34.7s)
```

After:
```
  Setting up Python environment.....done (1m14.7s)
```