feat: parser improvs

[lonerapier]

• update parser to add:
  • parsing_start as counter, counting each value in start line
  • parsing_header as counter, counting each new header
  • parsing_field_name as flag
  • parsing_field_value as flag
• adds match field name template
• adds field value extract template

TODOs:

• RFC 9112 states that, parsers should support multiple space separators between value (although not strictly). Currently, this isn't supported in our parser.
• When moving from headers -> body, parsing_header is incremented for first CRLF. So, counts a rogue header, which it shouldn't.
• Merge response + field value extractor proofs together

[Autoparallel]

quick review -- looks good.

Going to go into a more in-depth review by trying to use this all in codegen. Lfg