Merge #7542: Implement "feefilter" P2P message
0371797 modify release-notes.md and bips.md (Alex Morcos)
b536a6f Add p2p test for feefilter (Alex Morcos)
5fa66e4 Create SingleNodeConnCB class for RPC tests (Alex Morcos)
9e072a6 Implement "feefilter" P2P message. (Alex Morcos)