Update msg_sender() to return sender when input type is Input::Message

[bitzoic]

Description

This change reflects an issue experienced by an internal contributor where msg_sender().unwrap() would revert when sending a message. Currently, the sender is only returned when the input is of type Input::Coin.

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).
• 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.

[Braqzen]

I believe you should use input_message_recipient instead of input_message_sender because they will be the owner upon receiving the resource

[bitzoic]

I believe you should use input_message_recipient instead of input_message_sender because they will be the owner upon receiving the resource

Perhaps I'm misunderstanding, but why would we want the recipient when calling msg_sender()?

[Braqzen]

I believe you should use input_message_recipient instead of input_message_sender because they will be the owner upon receiving the resource

Perhaps I'm misunderstanding, but why would we want the recipient when calling msg_sender()?

Well, the high level method is called msg_sender() but the method being adjusted regards the owner of the inputs. When sent the owner of the message may be the sender field but the recipient will become the owner.

There was more talk of this, which yet again I forget the details, from @segfault-magnet for when and what the sender / recipient represent depending on when the message is constructed iirc.

[bitzoic]

Resolved by #6231