Function generate_bridge_client_key_and_write_to_file

pub fn generate_bridge_client_key_and_write_to_file(
    path: &PathBuf,
    use_ecdsa: bool,
) -> Result<(), Error>

Generate Bridge Client key (Secp256k1KeyPair or Ed25519KeyPair) and write to a file as base64 encoded flag || privkey.