Remove usage of stake::config

[programskillforverification]

close #36

[joncinque]

Hi there, I appreciate your time in looking at the issue, but unfortunately it will take more than just removing the usage in the instruction creator. This is a breaking change, so we'll need to do the same thing as the stake program, and pass in an unused account from single-pool down to the stake program. We'll also need to also modify the on-chain program to use the new account properly.

This is not a good first issue unfortunately, since it requires knowledge of native staking on Solana and also knowledge of this program. If you want to read more about the deprecation of config, be sure to read through the previous work doing this:

• ff cleanup: reduce_stake_warmup_cooldown anza-xyz/agave#470
• single-pool: Allow stake config to be anything in tests solana-labs/solana-program-library#6543