mw.Title: Correct handling of Unicode whitespace and bidi control characters

mw.Title: Correct handling of Unicode whitespace and bidi control characters

MediaWiki titles may not contain Unicode bidi control characters, e.g.
U+200E LEFT-TO-RIGHT MARK. They are silently stripped and such a
title is considered valid.

MediaWiki titles may not contain any whitespace other than a regular
space. Most of them are silently replaced with a regular space and
such a title is considered valid, but there are some (e.g. the tab
character) which make the title invalid. I'm not sure if this is an
intentional behavior, but I added a test case to verify it.

Bug: T143759
Change-Id: If8fad1f896027c5d93a62b0785923a39136c6a36