Merge bitcoin/bitcoin#34269: wallet: disallow creating new or restoring to an unnamed (default) wallet

75b704df9d wallettool: Disallow creating new unnamed wallets (Ava Chow)
5875a9c502 wallet: disallow unnamed wallets in createwallet and restorewallet (Ava Chow)
d30ad4a912 wallet, rpc: Use HandleWalletError in createwallet (Ava Chow)

Pull request description:

  We've been moving in the direction that all wallets must have a name. Therefore, we shouldn't allow creating new unnamed wallets. `createwallet`, `restorewallet`, and the wallet tool's `create` and `createfromdump` all now require the user to provide a non-empty wallet name when creating/restoring a wallet.

  The GUI is already enforcing this, but we were not enforcing it for RPCs or in the underlying `CreateWallet` and `RestoreWallet` functions.

  Wallet migration does still need to be able to restore unnamed wallets, so there is a new argument to `RestoreWallet` to explicitly allow that behavior for migration only.

ACKs for top commit:
  rkrux:
    lgtm ACK 75b704df9d
  polespinasa:
    re ACK 75b704df9d

Tree-SHA512: 8bde76d0b091e9276788c69412934af3426da2a7a69a00f94072d36c1a075cd41744ecdd5fef2b72870c1351b76aae061f124f716bb23f4839be20c464fc5ebd

test/functional/test_framework/test_node.py

@@ -907,7 +907,6 @@ class TestNode():
     def wait_until(self, test_function, timeout=60, check_interval=0.05):
         return wait_until_helper_internal(test_function, timeout=timeout, timeout_factor=self.timeout_factor, check_interval=check_interval)
 
-
 class TestNodeCLIAttr:
     def __init__(self, cli, command):
         self.cli = cli