Extract transaction-context crate

[kevinheavey]

Problem

solana_sdk::transaction_context imposes a solana_sdk dep on solana_transaction_status_client_types

Summary of Changes

• Move to its own crate and re-export with deprecation notice
• transaction_context.rs was making use of the full feature of solana-sdk for code using debug_assertions. Add a debug_assertions feature to the new crate to replace the full feature.
• Make serde and bincode optional in the new crate
• Add doc_auto_cfg like in add doc_auto_cfg to relevant sdk crates #3121

[joncinque]

Looks great overall! Just a question on the name of the feature, I think you took the right approach.

I looked for another potential crate to host this type, but it's really used all over the place, so a separate crate makes sense.

[joncinque]

Sorry, one last bit

[joncinque]

Looks good to me! @yihau can you accept solana-transaction-context?