Increase Safety when introspecting transaction inputs

[bitzoic]

Description

When using the inputs.sw library of the std-lib, if a bad input was given to the functions or a transaction did not exist, the functions would revert. Instead, they now return options so error may be caught.

Fixes

• input_pointer now returns a pointer over a u64 and is private.

Breaking

There are a number of breaking changes in function return types.

• predicate_address() now returns an Option<Address>.
  Before:

let my_predicate_address: Address = predicate_address();

After

let my_predicate_address: Address = predicate_address().unwrap();

• input_type() now returns an Option<Input>.
  Before:

let my_input_type: Input = input_type(0);

After:

let my_input_type: Input = input_type(0).unwrap();

• input_predicate_data() now returns an Option<T>.
  Before:

let my_data: u64 = input_predicate_data::<u64>(0);

After:

let my_data: u64 = input_predicate_data::<u64>(0).unwrap();

• input_predicate() now returns an Option<Bytes>.
  Before:

let my_input_predicate: Bytes = input_predicate(0);

After:

let my_input_predicate: Bytes = input_predicate(0).unwrap();

• input_message_sender() now returns an Option<Address>.
  Before:

let my_message_sender: Address = input_message_sender(0);

After:

let my_message_sender: Address = input_message_sender(0).unwrap();

• input_message_recipient() now returns an Option<Address>.
  Before:

let my_message_recipient: Address = input_message_recipient(0);

After:

let my_message_recipient: Address = input_message_recipient(0).unwrap();

• input_message_data_length() now returns an Option<u64>.
  Before:

let my_message_data_length: u64 = input_message_data_length(0);

After:

let my_message_data_length: u64 = input_message_data_length(0).unwrap();

• input_message_data() now returns an Option<Bytes>.
  Before:

let my_input_message_data: Bytes = input_message_data(0);

After:

let my_input_message_data: Bytes = input_message_data(0).unwrap();

• input_pointer() now returns an Option<raw_ptr> and is private
  Before:

let my_input_pointer: u64 = input_pointer(0);

After:

let my_input_pointer: raw_ptr = input_pointer(0).unwrap();

• input_message_nonce() now returns an Option<b256>
  Before:

let my_message_nonce: b256 = input_message_nonce(0);

After:

let my_message_nonce: b256 = input_message_nonce(0).unwrap();

Closes #6216

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[K1-R1]

LGTM; just an optional nit