Add exception to snake case in instruction name for Anchor

[GuidoDipietro]

Describe the bug
Anchor instructions named something_number where "number" is an integer fail from the client side with "Fallback instructions are not supported" as it derives the discriminator incorrectly.

To Reproduce
Name an instruction instruction_1 on the CIDL and try to call it.

Extension (mark with an X the extension):

• Solana Native [ ]
• Solana Anchor [x]

Solution
Match /_([0-9])*/ and replace by $(1). Basically, remove the last underscore if the instruction name finishes with _number.

[GuidoDipietro]

I just solved it