scripted-diff: Rename mininode to p2p

-BEGIN VERIFY SCRIPT-
sed -i 's/\.mininode/\.p2p/g' $(git grep -l "mininode")
git mv test/functional/test_framework/mininode.py test/functional/test_framework/p2p.py
-END VERIFY SCRIPT-

test/functional/p2p_dos_header_tree.py

@@ -8,7 +8,7 @@ from test_framework.messages import (
     CBlockHeader,
     FromHex,
 )
-from test_framework.mininode import (
+from test_framework.p2p import (
     P2PInterface,
     msg_headers,
 )