[net processing] Extract addr send functionality into MaybeSendAddr()

Summary:
Reviewer hint: review with

git diff --color-moved=dimmed-zebra --ignore-all-space

This is a backport of core#21236 [3/6]
https://github.com/bitcoin/bitcoin/pull/21236/commits/ad719297f2ecdd2394eff668b3be7070bc9cb3e2

Depends on D10916

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10917