Use snake_case for identifier

src/bdk.udl

@@ -1,6 +1,6 @@
 namespace bdk {
   [Throws=BdkError]
-  ExtendedKeyInfo generate_extended_key(Network network, MnemonicType mnemonicType, string? password);
+  ExtendedKeyInfo generate_extended_key(Network network, MnemonicType mnemonic_type, string? password);
   [Throws=BdkError]
   ExtendedKeyInfo restore_extended_key(Network network, string mnemonic, string? password);
 };