feat: Add deprecated attribute

[ghost]

Description

fn main() {
    deprecated();
}

#[deprecated]
fn deprecated() {}

> nargo check
warning: use of deprecated function deprecated
  ┌─ /home/work/subject/oliver/noir/app/src/main.nr:2:5
  │
2 │     deprecated();
  │     ----------

Constraint system successfully built!

Problem

Resolves #879

PR Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[TomAFrench]

Can you add tests showing that we can display custom deprecation messages which should be defined inside the #[deprecated] tag? We should check that these are usable on foreign/oracle/builtin functions as well.

[kevaundray]

Agree that we should add tests to see how this plays with other attributes.

Also agree, it would be good to have the reason for deprecation, seems to be quite easy to add it like we have with Oracle attribute for example and retain that information until we need to emit a warming. It is not hard blocking for this PR though (wasn't in the issue that it resolves)

[ghost]

As of now, only one attribute per function is currently supported.

noir/crates/noirc_frontend/src/ast/expression.rs

Lines 335 to 336 in ce37718

	// XXX: Currently we only have one attribute defined. If more attributes are needed per function, we can make this a vector and make attribute definition more expressive
	pub attribute: Option<Attribute>,

I'm not sure how to implement it correctly, but I'll give it a try.

[kevaundray]

As of now, only one attribute per function is currently supported.

noir/crates/noirc_frontend/src/ast/expression.rs

Lines 335 to 336 in ce37718

	// XXX: Currently we only have one attribute defined. If more attributes are needed per function, we can make this a vector and make attribute definition more expressive
	pub attribute: Option<Attribute>,

I'm not sure how to implement it correctly, but I'll give it a try.

We can open up another issue for multiple attributes, as that may introduce scope creap. Can you just look into adding the message?

[TomAFrench]

Can you add a test which shows that this warning gets created correctly when parsing a program?

[jfecher]

@TomAFrench pending re-review

[TomAFrench]

To match Rust, we should do #[deprecated = "message"] rather than #[deprecated("message")] https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute

We'd probably want to adjust this for the other attributes as well though I think so this can be pushed into a diff PR.