Remove or Fix Ignores

Remove / Fixes ignored parts.

Except for a few things:

• local_user_hyd_bloc and perm_hyd_bloc as those are 1:1 "forks" of hydrated_bloc.
• lines_longer_than_80_chars in string source files.
• invalid_use_of_protected_member as I don't know how to fix them yet.
• prefer_mixin at two occurrences where the class is correctly used (Added a comment providing the reasoning).
• unnecessary_lambda where a tear-off would have broken symmetry between two lines.
• avoid_classes_with_only_static_members turned off globally for sanity.