MessageTemplate - Allow 'workflow'/'valueName' as aliases. Consolidate alias bits.

MessageTemplate - Allow 'workflow'/'valueName' as aliases. Consolidate alias bits.

The params given to `MessageTemplate::sendTemplate()` are evolving. But they are also
exposed via hook. Blerg.

This technically does two things:

1. It takes a couple of bits which are responsible for aliasing/transitioning specific
   params, and it moves them to a common `$sync()` function.

2. It deprecates `valueName` in favor of `workflow`, and it updates the hook test
   accordingly.