Refactor ticket receipt code for `sc-rollup <-> originated`

The code for ticket receipt for sc-rollup <-> originated can be improved in several ways:

• Share code that scans value for (unparsed_ticket_token, amount) pairs in RPC.ml and apply.ml
  • Ref: !6949 (comment 1189433286)
• Share code between sc-rollup->originated and originated->sc-rollup
  • Ref: !6949 (comment 1189494262)