[avalanche] Send proof inventories

Summary:
Add the proof inventories in the inv messages. For now the proofs are
only added manually via the sendavalancheproof RPC.
This is heavily based on the current implementation for transactions.

Depends on D9654.

Supersedes D9489 and D9493.

Ref T1611.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Subscribers: PiRK

Maniphest Tasks: T1611

Differential Revision: https://reviews.bitcoinabc.org/D9650