Add batch instruction

[abelmarnk]

This PR adds the batch instruction to the token-2022 program, implementation drawn from here and originally proposed here.

The purpose is to allow the execution of multiple token instructions in a single program instruction – e.g., it is possible to execute multiple instructions in a single CPI call, which saves at least 1000 CUs (CPI base fee) for each additional instruction.

Scope

• Update the TokenInstruction instruction variants(regular and POD) and associated tests
• Add de/ser helper for the TokenInstruction variant
• Update the processor code
• Update the processor tests

It closes #787.

[abelmarnk]

@joncinque, I didn't add client code because the main purpose of the instruction seems to be for use with CPI, would it still be better to add it in as an instruction that takes raw bytes as arguments?