Set Template-provided properties with a separate BindingPriority

[kekekeks]

Right now template-provided properties are being set with LocalValue priority which makes them to take precedence over any style setters. That's really inconvenient since it makes some control aspects impossible to style without changing the entire ControlTemplate.

We should have a separate TemplateProperty binding priority which can be overridden by StyleTrigger binding priority.

[grokys]

I'm not even sure we'd need a separate priority. I think using Style priority would do it.

[grokys]

Actually I think TemplatedParent priority is the correct one (should probably be renamed to Template)