Refactor python rules

The goal of this cl is to simplify the python rules,
mostly by removing the "decorator" pattern that they
currently use, and instead making separate module
types for libraries, binaries, and tests that inherit
from each other.

Bug: 259718110
Test: Verified ninja files are unchanged (they only change in the list of soong sources because I added/deleted files)
Change-Id: I1e836e2cc4782c7818f91db7df7895de3b8db7ca