[rpc] Tidy up reporting of buried and ongoing softforks

This combines reporting of buried (formally ISM) softfork deployments
and BIP9 versionbits softfork deployments into one JSON object in the
getblockchaininfo return object.

test/functional/test_framework/util.py

@@ -344,7 +344,7 @@ def delete_cookie_file(datadir):
 
 def get_bip9_status(node, key):
     info = node.getblockchaininfo()
-    return info['bip9_softforks'][key]
+    return info['softforks'][key]['bip9']
 
 def set_node_times(nodes, t):
     for node in nodes: