Feat/policy hooks

[0xRigel-squads]

Changes

Policy Rent Collector

• Introduces the same rent collector mechanism as transactions/proposals/batches for policy accounts. Whoever pays for the opening of a given policy, will also be rebated if that policy ever gets closed
• Gets enforced on RemovePolicy settings action

Account Data Constraints

• Function the same way as instruction data constraints, except on the account data & account owner of a given account pre-execution

Program Interaction Hooks

• Support for pre- & posthooks on the program_interaction_policy. This enforces the execution of a set instruction before and/or after execution of the inner instructions.
• Supports custom instruction data, accounts (with constraints) as well as passing inner instructions & accounts
• Signed by hook authority (constant PDA), to enable validation of source program