[Code Style] Changes in tag standards: Administrator Components

This pull should fix the issue detailed here: joomla/coding-standards#80

I have broken in parts this original pull #4590 to make it easy for review. This pull is contains only the administrator components changes.
The components/, ... are going to be sent in different pulls.

This pull is related to #4603, #4625, #4632 and #4617.

This pull also includes and closes #4589, because it was conflicting with it, so I just merged it into this one in a different commit.