refactor!: Remove node parameter from Circuit

[aborgna-q]

The update to hugr 0.15 added a Node associated type to HugrView.
Over here, that got implemented as a new type parameter in Circuit,

struct Circuit<T = Hugr, N = Node>

All impl blocks however restrain it to the specific hugr support,

impl<T: HugrView> Circuit<T, T::Node> { ... }

Given how both types are connected, we should be using T::Node directly since an unrelated node type is not usable here.

This PR changes the definition to

pub struct Circuit<T: HugrView = Hugr>

As this is a breaking change, it can wait until the next breaking release.

BREAKING CHANGE: Removed node type parameter from Circuit

[doug-q]

Looks great. Not approving because we don't want to merge yet.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.58%. Comparing base (9b31135) to head (df8324f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #824   +/-   ##
=======================================
  Coverage   82.58%   82.58%           
=======================================
  Files          65       65           
  Lines        8097     8097           
  Branches     7834     7834           
=======================================
  Hits         6687     6687           
  Misses       1005     1005           
  Partials      405      405           

Flag	Coverage Δ
python	82.12% <ø> (ø)
rust	82.60% <100.00%> (ø)

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[hugrbot]

This PR contains breaking changes to the public Rust API.

cargo-semver-checks summary

--- failure type_allows_fewer_generic_type_params: type now allows fewer generic type parameters ---

Description:
A type now allows fewer generic type parameters than it used to. Uses of this type that supplied all previously-supported generic types will be broken.
      ref: https://doc.rust-lang.org/cargo/reference/semver.html#trait-new-parameter-no-default
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.40.0/src/lints/type_allows_fewer_generic_type_params.ron

Failed in:
Struct Circuit allows 2 -> 1 generic types in /home/runner/work/tket2/tket2/PR_BRANCH/tket2/src/circuit.rs:37
Struct Circuit allows 2 -> 1 generic types in /home/runner/work/tket2/tket2/PR_BRANCH/tket2/src/circuit.rs:37