[avalanche] Answer getavaproofs message with short proof ids

Summary:
This diff introduces a new getavaproofs message, which which requests for an avaproofs message containing all the proofs short ids from the peer.

Notes:

• The name does not contain the "compact" mention like one might expect, due to the limitation in the command name to 12 chars.
• There is a theoretical limit of 21 millions proofs which could cause the node to generate a oversized message (limited to 2MiB). This will be taken care in a follow-up.

Depends on D11453.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Subscribers: sdulfari, deadalnix, tyler-smith

Differential Revision: https://reviews.bitcoinabc.org/D11388