Count the external (receiving) keys available in the keypool.
Declared in <wallet/wallet.h>
[[requires_capability(0x7fb955bcfc38), requires_capability(0x7fb94db84558), requires_capability(0x7fb95ab143d8), requires_capability(0x7fb959fb0fb8), requires_capability(0x7fb956cbb248)]]
size_t
KeypoolCountExternalKeys() const;
The number of external keys in the keypool.