Add a user-specified relative ordering for attributes

[jfecher]

Problem

Users cannot control which order their attributes run leading to issues such as #6143

Happy Case

We add two new attributes #[run_after(f)] and #[run_before(f)] which accept a function f as an argument and ensure that the attribute function they're applied to is run after or before the attribute function f.

For example:

#[run_after(derive)]
comptime fn check_if_eq_is_implemented(s: StructDefinition) {
    let eq = quote { Eq }.as_trait_constraint();
    assert(s.as_type().implements(eq));
}

We could also have a default step so that attributes can run before other attributes by default. If derive used this for example then there'd be no need for other attributes to have to know to run after it:

#[run_before(_)]
comptime fn derive(s: StructDefinition, traits: [TraitDefinition]) -> Quoted { ... }

Workaround

None

Workaround Description

No response

Additional Context

No response

Project Impact

None

Blocker Context

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response

[jfecher]

We decided to go with source ordering instead for greater predictability and easier debugging of attributes