feat: add inlining annotation + pass

[acl-cqc]

Intended as precursor to #1532: this adds the "Always" option only, but takes into account in its own pass, which raises an error if it cannot obey all the annotations.

Python interface is very WIP, not sure I've grokked everything there yet.

[codecov]

Codecov Report

❌ Patch coverage is 97.44898% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.60%. Comparing base (084c9de) to head (c955955).

Files with missing lines	Patch %	Lines
tket/src/passes/inline_always.rs	98.33%	3 Missing ⚠️
tket-py/tket/passes/__init__.py	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1449      +/-   ##
==========================================
+ Coverage   85.52%   85.60%   +0.07%     
==========================================
  Files         184      185       +1     
  Lines       29077    29271     +194     
  Branches    27876    28056     +180     
==========================================
+ Hits        24868    25057     +189     
- Misses       3075     3080       +5     
  Partials     1134     1134              

Flag	Coverage Δ
python	90.40% <86.66%> (-0.06%)	⬇️
qis-compiler	91.66% <ø> (ø)
rust	85.39% <98.34%> (+0.08%)	⬆️

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[hugrbot]

This PR contains breaking changes to the public Rust API.
Please deprecate the old API instead (if possible), or mark the PR with a ! to indicate a breaking change.

cargo-semver-checks summary

    Building tket v0.18.0 (current)
     Built [  45.319s] (current)
   Parsing tket v0.18.0 (current)
    Parsed [   0.120s] (current)
  Building tket v0.18.0 (baseline)
     Built [  43.166s] (baseline)
   Parsing tket v0.18.0 (baseline)
    Parsed [   0.106s] (baseline)
  Checking tket v0.18.0 -> v0.18.0 (assume minor change)
   Checked [   0.141s] 196 checks: 194 pass, 1 fail, 1 warn, 56 skip

--- failure enum_no_repr_variant_discriminant_changed: enum variant had its discriminant change value ---

Description:
The enum's variant had its discriminant value change. This breaks downstream code that used its value via a numeric cast like `as isize`.
      ref: https://doc.rust-lang.org/reference/items/enumerations.html#assigning-discriminant-values
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.47.0/src/lints/enum_no_repr_variant_discriminant_changed.ron

Failed in:
variant InlineAnnotation::BestEffort 0 -> 1 in /home/runner/work/tket2/tket2/PR_BRANCH/tket/src/metadata.rs:60
variant InlineAnnotation::Never 1 -> 2 in /home/runner/work/tket2/tket2/PR_BRANCH/tket/src/metadata.rs:62

--- warning partial_ord_enum_variants_reordered: enum variants reordered in #[derive(PartialOrd)] enum ---

Description:
A public enum that derives PartialOrd had its variants reordered. #[derive(PartialOrd)] uses the enum variant order to set the enum's ordering behavior, so this change may break downstream code that relies on the previous order.
      ref: https://doc.rust-lang.org/std/cmp/trait.PartialOrd.html#derivable
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.47.0/src/lints/partial_ord_enum_variants_reordered.ron

Failed in:
InlineAnnotation::BestEffort moved from position 1 to 2, in /home/runner/work/tket2/tket2/PR_BRANCH/tket/src/metadata.rs:60
InlineAnnotation::Never moved from position 2 to 3, in /home/runner/work/tket2/tket2/PR_BRANCH/tket/src/metadata.rs:62

   Summary semver requires new major version: 1 major and 0 minor checks failed
   Warning produced 1 major and 0 minor level warnings
  Finished [  90.135s] tket
  Building tket-qec v0.1.0 (current)
     Built [  39.059s] (current)
   Parsing tket-qec v0.1.0 (current)
    Parsed [   0.006s] (current)
  Building tket-qec v0.1.0 (baseline)
     Built [  39.023s] (baseline)
   Parsing tket-qec v0.1.0 (baseline)
    Parsed [   0.006s] (baseline)
  Checking tket-qec v0.1.0 -> v0.1.0 (assume minor change)
   Checked [   0.015s] 196 checks: 196 pass, 56 skip
   Summary no semver update required
  Finished [  79.288s] tket-qec
  Building tket-qsystem v0.24.0 (current)
     Built [  45.172s] (current)
   Parsing tket-qsystem v0.24.0 (current)
    Parsed [   0.026s] (current)
  Building tket-qsystem v0.24.0 (baseline)
     Built [  44.494s] (baseline)
   Parsing tket-qsystem v0.24.0 (baseline)
    Parsed [   0.026s] (baseline)
  Checking tket-qsystem v0.24.0 -> v0.24.0 (assume minor change)
   Checked [   0.060s] 196 checks: 196 pass, 56 skip
   Summary no semver update required
  Finished [  91.201s] tket-qsystem

[aborgna-q]

Some comments, mostly about differentiating the two passes.

Although from the technical side it makes sense to have two of them (we need to do different kinds of traversals for each), I struggle to justify having the split passes from the user point of view.
When would I want to "inline some of the annotated functions, but not the others that I've also annotated"?

[aborgna-q]

Suggested change

	f_id.metadata["tket.inline"] = "always"
	f_id.metadata[InlineAnnotation] = "always"

[aborgna-q]

This needs updates in the docs and in from_json

[aborgna-q]

We should explain what are the differences between this pass an InlineFunctionsPass, not only here but in the other pass' docs and on the python definitions too.

[aborgna-q]

I'm thinking we should treat Always as BestEffort here. We won't inline every occurrence, but at least we should inline the ones we can.

[aborgna-q]

Would probably merit a mention to the different inline passes.