[avalanche] Evaluate the presence of a proof based on remotes

Summary:
Add a getter to evaluate the proof presence based on the remotes. It needs both a majority of nodes and a majority of stakes, otherwise it is inconclusive.

Depends on D14663.

Test Plan:

ninja check-avalanche-peermanager_tests

Reviewers: #bitcoin_abc, PiRK, bytesofman

Reviewed By: #bitcoin_abc, PiRK, bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D14664