This makes KWin switch to in-tree copy of KWaylandServer codebase.
KWaylandServer namespace has been left as is. It will be addressed later
by renaming classes in order to fit in the KWin namespace.
In plasma code, it's more common to see `/** ... */` doxygen comments
rather than `/** ... **/`.
This change fixes up doxygen comment terminators to prevent inconsistency
issues.
- Drop the v0 support, it is no longer used by anything
- Adapt the text-input related methods in seat interface to include
versioning, this will be useful for when zwp_text_input_v3 support is
included in kwayland-server
- Refactor SeatInterface to get rid of globalTextInput, it is no longer
needed with the new approach
- Refactor out the ContentHints and ContentPurpose enums in separate
header file which can be shared by zwp_text_input_v2/3 implementation
Co-Author: Bhushan Shah <bshah@kde.org>