csharp: Refactor annotation selection function
Better names to convey their intent and formatting.
Removing the hardcoded return from them will also free the return list
to be used for @out parameters as they have similar semantics to
return, different from regular @in parameters. This change in
behavior will come in a future commit, and explains why are are keeping
both lists for now despite being essentially the same.
Test Plan: Run existing tests
Reviewers: felipealmeida, brunobelo, jptiz, YOhoho
Reviewed By: jptiz
Maniphest Tasks: T8515
Differential Revision: https://phab.enlightenment.org/D10827