Extract OffchainConfig types and share with other Gauntlet implementations

[krebernisak]

This type looks useful across Gauntlet implementations. Also, the validation, which can be parameterized and used by specific implementations.

Do you think it's time we extract this, perhaps into gauntlet-core's ocr2 package, and reuse on Solana?

• https://github.com/smartcontractkit/chainlink-solana/blob/e87a8aea0ad97485eca3f044cd0aba21af5dca5f/gauntlet/packages/gauntlet-solana-contracts/src/commands/contracts/ocr2/offchainConfig/write.ts#L14
• https://github.com/smartcontractkit/chainlink-solana/blob/e87a8aea0ad97485eca3f044cd0aba21af5dca5f/gauntlet/packages/gauntlet-solana-contracts/src/commands/contracts/ocr2/offchainConfig/write.ts#L143

Originally posted by @krebernisak in #19 (comment)