If there are multiple external signers, `GetExternalSigner()` will
just pick the first one in the list. If the user has two or more
hardware wallets connected at the same time, he might not notice this.
This PR adds a check and fails with suitable message.
The previous diff touched most files in ./test/, so bump the headers to
avoid having to touch them again for a bump later.
-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./test/
-END VERIFY SCRIPT-
This commit moves the ExternalSigner class and RPC methods out of the wallet module.
The enumeratesigners RPC can be used without a wallet since #21417.
With additional modifications external signers could be used without a wallet in general, e.g. via signrawtransaction.
The signerdisplayaddress RPC is ranamed to walletdisplayaddress because it requires wallet context.
A future displayaddress RPC call without wallet context could take a descriptor argument.
This commit fixes a rpc_help.py failure when configured with --disable-wallet.
