textproc/py-docutils: Fix/improve console scripts packaging

Remove custom script symlink/packaging routine (and pkg-plist) that adds
versions without .py filename suffix, in favour of what upstream provides by
default.

The manually maintained script list in the port was incomplete, so not all
scripts were processed, producing an inconsistent experience (if not POLA
violation) for users, and proves the mechanism itself is difficult to keep
up-to-date and accurate. Additionally, all upstream documentation refers to
these tools by their suffixed names.

While I'm here:

• Pet potlint (USES/USE_* order)
• Add test target to make future QA easier/more thorough.

Approved by: koobs (python, maintainer)