[Chronik] Add eMPP (eCash Multi Pushdata Protocol)

Summary:
Purpose of this is to allow multiple protocols per OP_RETURN, which allows us to use protocols like SLPv2.

Specification can be found here: https://www.notion.so/ecashbuilders/eCash-Multi-Pushdata-Protocol-11e1b991071c4a77a3e948ba604859ac

Test Plan: ninja check-crates

Reviewers: Fabien, #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Subscribers: Mengerian, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D13949