Transition from maps to lists of named subobjects

[robscott]

What happened:
Maps were used several places throughout the API. Including, but likely not limited to:

• Query Param Matching (Switching Header and Query Param matching to use lists #657)
• Header Matching (Switching Header and Query Param matching to use lists #657)
• Header Modification (assignee: @hbagdi, httproute: use lists insteads of maps for HTTPRequestHeaderFilter #681)

This is also the case for TLS options, but I think it's likely appropriate in that case.

What you expected to happen:
Lists of named subojects should be used to match the API conventions.

[hbagdi]

@robscott I have opened up #681 to handle the header modifier filter. Do we want to go ahead with TLS or not? I don't have strong feelings either way.