This PR changes the functional tests to have a consistent naming scheme:
tests for individual RPC methods are named rpc_...
tests for interfaces (REST, ZMQ, RPC features) are named interface_...
tests that explicitly test the p2p interface are named p2p_...
tests for wallet features are named wallet_...
tests for mining features are named mining_...
tests for mempool behaviour are named mempool_...
tests for full features that aren't wallet/mining/mempool are named feature_...
Rationale: it’s sometimes difficult for new contributors to know what’s already covered by existing tests and where new tests should be added. Naming in a consistent fashion makes it easier to see what’s already covered at a glance.