Split message filtering functionality into distinct operators

[glopesdev]

This PR deprecates the existing FilterMessage operator and introduces two new operators: FilterMessageType which is a general operator that can work for all messages; and FilterRegister which can be extended by different device packages to filter device-specific messages.

Both of these operators expose a FilterType property specifying whether the filter includes or excludes all messages matching its criteria. For consistency, we also drop the message type property from the Parse operators. The filter in Parse is always inclusive-only since Parse cannot promise to know how to handle arbitrary messages outside its specified register.

Fixes #61