randr: Add provider object support (RandR v1.4)

randr: Add provider object support (RandR v1.4)

With RandR 1.4 provider objects have been introduced. "A provider object
represents a GPU or virtual device providing services to the X server."

To handle provider objects the following requests have been added:
    - GetProviders
    - GetProviderInfo
    - SetProviderOffloadSink
    - SetProviderOutputSource
    - ListProviderProperties
    - QueryProviderProperty
    - ConfigureProviderProperty
    - ChangeProviderProperty
    - DeleteProviderProperty
    - GetProviderProperty

And the Notify event got 3 new subcodes:
    - ProviderChange
    - ProviderProperty
    - ResourceChange

v2:
- add missing name field to GetProviderInfo
v3:
- changed ProviderCapability enum
  o replaced <value> with <bit>
  o removed None
- replaced "alignment pad list" with commented out <pad align="4"/> to
  be prepared for future enhancements
- add brief description to commit msg about additions

Signed-off-by: Daniel Martin <consume.noise@gmail.com>
Signed-off-by: Peter Harris <pharris@opentext.com>