fix: improve write_program logic; add tests

[MicaiahReid]

This PR:

• fixes write_program fn in locker.rs
  • to summarize, when you call set_account on litesvm, it checks if that account is executable and loads it into a cache of programs. I wasn't aware of this. So when we would 1. write program account, 2. write program data account, the program account wasn't being re-indexed with the new program data. This would cause program updates to fail beyond the initial program written
• slimmed down the minimum program we deploy
  • when you write am account using set_account, if the account is executable, it's also going to verify that there is an associated program data account, and verify the ELF of the program. So, if a program account is being written without the data account, we're pushing a minimal ELF. I've updated this to be smaller
• tests for the edge cases that I hit