pip_compile macro produces differently-named rule

[alexeagle]

A user who wrote pip_compile in their BUILD file might query:

% bazel query --output=label_kind requirements:all
_pip_compile rule //requirements:requirements.all
alias rule //requirements:requirements.all.update
_pip_compile_test rule //requirements:requirements.all_test

It's not desirable that the names here don't match the name in the BUILD file.

• Breaks --test_lang_filters=-pip_compile - you'd have to --test_lang_filters=-_pip_compile with the private name
• If you want to write the query to find only pip_compile rules you have to account for the underscore
• Editors or tooling that does a query to show the targets in the file will show something that mismatches

Note, I'll send a PR to fix this shortly