This adds a "python.js" target to the Makefile. We enable the raw
node fs mode as suggested by @thomasballinger as it will make running
the test suite under node easier, c.f.
emmatyping/python-wasm#36.

The wasm_asset.py script is updated to include the test module. Care is
taken to skip compiling the Python files that are examples of bad syntax
or encoding.

This also turns on memory growth as early into the test suite I was
running into OOMs.

Co-authored-by: Christian Heimes <christian@python.org>