Adaptive Inflation: carbonate operations

AI adds new operations, implemented as entrypoints to implicit accounts: stake, unstake, finalize_unstake, set_delegate_parameters. These operations need to be carbonated.

Ideally we should try to have a fixed cost for them so that they are more predictable. Let's see what worst case scenarios give.

This is done in three steps:

• Add a get_delegate_status function to avoid duplicating code or accessing the same storage multiple times: !9400 (merged) (not mandatory).
• Optimize some code to make it less expansive gas-wise: !9403 (merged). (It answers this comment.)
• Add gas consumption: !9319 (merged).