Tezlink/Kernel/MIR : Use Entrypoint instead of FieldAnnotation for interpreter entry

What

Refactors the way entrypoints are handled in Michelson interpreter and Tezlink execution by introducing direct Entrypoint usage instead of FieldAnnotation.

Why

FieldAnnotation was previously used as an intermediary representation for entrypoints, adding unnecessary complexity. Using Entrypoint directly improves type safety, consistency, and reduces conversion overhead.

How

• Implemented From<Entrypoint> for FieldAnnotation
• Updated ContractScript::wrap_parameter and ContractScript::interpret to accept Entrypoint directly instead of FieldAnnotation.
• Adjusted execute_smart_contract and transfer in tezos_execution to pass Entrypoint directly.

Manually testing the MR

Run all tests to verify entrypoint handling:

cd etherlink/kernel_latest/tezos_execution
cargo test

Also run MIR unit tests:

cd contrib/mir
cargo test

Ensure that contracts with default and custom entrypoints execute correctly.