Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
Create an installable pyodide-build package. Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
package:
  name: freesasa
  version: 2.1.0
source:
  sha256: dca2a71f5a315aff3ad8ee96130d0e17003265d82241378ffc0dcb0f98bf2203
  url: https://files.pythonhosted.org/packages/a8/af/66991b63b705cd1e1c77fdaec157747275ba5c27b5c9dff7a2e35a43477a/freesasa-2.1.0.tar.gz
test:
  imports:
  - freesasa

package:
  name: freesasa
  version: 2.1.0
source:
  sha256: dca2a71f5a315aff3ad8ee96130d0e17003265d82241378ffc0dcb0f98bf2203
  url: https://files.pythonhosted.org/packages/a8/af/66991b63b705cd1e1c77fdaec157747275ba5c27b5c9dff7a2e35a43477a/freesasa-2.1.0.tar.gz
test:
  imports:
  - freesasa
