rpc: deprecate addresses and reqSigs from rpc outputs

1) add a new sane "address" field (for outputs that have an
   identifiable address, which doesn't include bare multisig)
2) with -deprecatedrpc: leave "reqSigs" and "addresses" intact
   (with all weird/wrong behavior they have now)
3) without -deprecatedrpc: drop "reqSigs" and "addresses" entirely,
   always.

test/functional/wallet_hd.py

@@ -132,7 +132,7 @@ class WalletHDTest(BitcoinTestFramework):
         keypath = ""
         for out in outs:
             if out['value'] != 1:
-                keypath = self.nodes[1].getaddressinfo(out['scriptPubKey']['addresses'][0])['hdkeypath']
+                keypath = self.nodes[1].getaddressinfo(out['scriptPubKey']['address'])['hdkeypath']
 
         if self.options.descriptors:
             assert_equal(keypath[0:14], "m/84'/1'/0'/1/")