While at it, also remove unnecessary "#!/usr/bin/env python3" in files
that only get imported, and adjust other empty/comment lines in the
beginnings of the files for consistency.
This makes files easier to read, and makes the pmbootstrap codebase more
consistent with the build.postmarketos.org codebase.
Replace the "Add topdir to import path" boilerplate lines in each test
file with a simple "import pmb_test". Use the "# noqa" comment if
"pmb_test" is not used further in the test file, so flake8 does not
complain about an unused module.
Make the path to the testdata available as pmb_test.const.testdata, and
use pmb.config.pmb_src to access the topdir in all tests.
This is in preparation for new "pmbootstrap status" related tests, which
will have shared test code in test/pmb_test/. Also, this makes the
pmbootstrap codebase more consistent with the bpo codebase, which has a
similar "import bpo_test" mechanism.
Packages ending in -dev: just assume that the originating aport has the
same pkgname, except for the -dev at the end. Otherwise we may end up
with the wrong package.
For example, if something depends on plasma-framework-dev, and
plasma-framework is in Alpine, but plasma is in pmaports, then the
regular guess_main() algorithm below would pick plasma instead of
plasma-framework.
Fixes: build.postmarketos.org#52
Move find_aport() and find_aport_guess_main() from pmb/build/other.py
to the new file pmb/helpers/pmaports.py.
Finding aports is not only needed when building packages, hence it
makes sense to move it out of pmb.build. The pmb/helpers/pmaports.py
file will have more pmaports related functions in a follow up commit.
