[net] Signal NODE_COMPACT_FILTERS if we're serving compact filters.

Summary:

If -peerblockfilters is configured, signal the NODE_COMPACT_FILTERS
service bit to indicate that we are able to serve compact block filters,
headers and checkpoints.

Partial backport (2/3) of core PR19070:
https://github.com/bitcoin/bitcoin/pull/19070/commits/132b30d9c84f2a8053714a438f227b583a89a9ea

Depends on D8730.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D8731