Component Process API Remix

[ianjosephwilson]

• Add ComponentProcessor extension point with example test
• Drop middleware api, "component object capturing", for now.
• Alter prep_component_kwargs
  • take in additional args via provided_attrs
  • add conditional flags to raise on positional only arguments and/or missing arguments
• Factor out embedded template extraction to "clear up" component processing

[ianjosephwilson]

This is closer but we should consider the middleware "concept" in #119.