[x/programs] Improve State-keys & Argument Passing

[samliok]

This PR improves argument passing from rust programs to host functions. It also removes the need to call the .to_vec() function on StateKeys, and generalizes external function calls by defaulting to borsh serialization.

Changes

• All argument types are now serialized using borsh when being passed to/from host.
• All arguments passed in/from the host are SmartPtr' which are int64 with the format [length][ptr]. Length and Ptr are 4 bytes each.
  • improves function signatures
    • ex. fn _put(caller_id: i64, key: *const u8, value: *const u8) -> i32;
    • instead of fn _put(caller_id: i64, key_ptr: *const u8, key_len: usize, value_ptr: *const u8, value_len: usize) -> i32;
  • this removes the need for the len host function call.
  • get(key) no longer requires calling the len host function call
• add an Into<Key> implementation for the #[state_keys] proc macro
• update call_program function to require BorshSerialize instead of Argument trait
  • improves usability for call_program & external function calls
  • the params! declarative macro serializes arguments required for external function calls
• Update go to use SmartPtr and consolidate associated helper functions into runtime/utils.go

also a small ux improvement from macro change

before

    program
        .state()
        .store(StateKey::TotalSupply.to_vec(), &123456789_i64)
        .expect("failed to store total supply");

now

    program
        .state()
        .store(StateKey::TotalSupply, &123456789_i64)
        .expect("failed to store total supply");

[richardpringle]

🚀