feat(data_structures): add AnyInlineString trait

[overlookmotel]

Add AnyInlineString trait. Due to limitations in Rust const generics, this is required to define a trait which is generic over InlineStrings with varying capacities.

This won't compile:

trait MyTrait {
    const CAPACITY: usize;
    fn get_str(&self) -> InlineString<Self::CAPACITY, u8>;
}

You can achieve the same thing with AnyInlineString (and this will compile):

trait MyTrait {
    type Str: AnyInlineString;
    fn get_str(&self) -> Self::Str;
}

[overlookmotel]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat(data_structures): add AnyInlineString trait #10857 👈 (View in Graphite)
• feat(data_structures): add InlineString::as_mut_str method #10856
• perf(data_structures): optimize InlineString #10850
• main

---

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #10857 will not alter performance

_{Comparing 05-07-feat_data_structures_add_anyinlinestring_trait (aabc016) with 05-06-feat_data_structures_add_inlinestring_as_mut_str_method (dde60ff)}

Summary

✅ 36 untouched benchmarks

[overlookmotel]

We have no use for this at present - I made this for something I was working on which I've now abandonned. So closing.