Merge bitcoin#20125: rpc, wallet: Expose database format in getwallet…

…info

624bab0 test: add coverage for getwalletinfo format field (Jon Atack)
5e737a0 rpc, wallet: Expose database format in getwalletinfo (João Barbosa)

Pull request description:

  Support for sqlite based wallets was added in bitcoin#19077. This PR adds the `format` key in `getwalletinfo` response, that can be `bdb` or  `sqlite`.

ACKs for top commit:
  jonatack:
    Tested ACK 624bab0
  laanwj:
    Code review ACK 624bab0.
  MarcoFalke:
    doesn't hurt ACK 624bab0
  hebasto:
    ACK 624bab0, tested on Linux Mint 20 (x86_64).
  meshcollider:
    utACK 624bab0

Tree-SHA512: a81f8530f040f6381d33e073a65f281993eccfa717424ab6e651c1203cbaf27794dcb7175570459e7fdaa211565bc060d0a3ecbe70d2b6f9c49b8d5071e4441c

test/functional/wallet_descriptor.py

@@ -22,13 +22,17 @@ def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
 
     def run_test(self):
+        wallet_info = self.nodes[0].getwalletinfo()
+        assert_equal(wallet_info['format'], 'bdb')
+
         # Make a descriptor wallet
         self.log.info("Making a descriptor wallet")
         self.nodes[0].createwallet(wallet_name="desc1", descriptors=True)
 
         # A descriptor wallet should have 100 addresses * 1 type = 100 keys
         self.log.info("Checking wallet info")
         wallet_info = self.nodes[0].getwalletinfo()
+        assert_equal(wallet_info['format'], 'sqlite')
         assert_equal(wallet_info['keypoolsize'], 100)
         assert_equal(wallet_info['keypoolsize_hd_internal'], 100)
         assert 'keypoololdest' not in wallet_info