refactor: move PersistentHugr into separate crate

[lmondada]

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 89.79592% with 5 lines in your changes missing coverage. Please review.

Project coverage is 82.09%. Comparing base (37a5151) to head (0f17e94). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
hugr-persistent/src/trait_impls.rs	57.14%	3 Missing :warning:
hugr-persistent/src/parents_view.rs	50.00%	1 Missing :warning:
hugr-persistent/src/state_space.rs	90.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2277      +/-   ##
==========================================
- Coverage   82.16%   82.09%   -0.07%     
==========================================
  Files         242      241       -1     
  Lines       43935    43888      -47     
  Branches    39773    39726      -47     
==========================================
- Hits        36098    36030      -68     
- Misses       5855     5877      +22     
+ Partials     1982     1981       -1     

Flag	Coverage Δ
python	85.48% <ø> (ø)
rust	81.73% <89.79%> (-0.08%)	:arrow_down:

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[hugrbot]

This PR contains breaking changes to the public Rust API.

cargo-semver-checks summary

--- failure enum_missing: pub enum removed or renamed ---

Description:
A publicly-visible enum cannot be imported by its prior path. A `pub use` may have been removed, or the enum itself may have been renamed or removed entirely.
      ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.41.0/src/lints/enum_missing.ron

Failed in:
enum hugr_core::hugr::persistent::walker::PinNodeError, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker.rs:333
enum hugr_core::hugr::persistent::serial::SerialCommitData, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/state_space/serial.rs:11
enum hugr_core::hugr::persistent::InvalidCommit, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/state_space.rs:474

--- failure module_missing: pub module removed or renamed ---

Description:
A publicly-visible module cannot be imported by its prior path. A `pub use` may have been removed, or the module may have been renamed, removed, or made non-public.
      ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.41.0/src/lints/module_missing.ron

Failed in:
mod hugr_core::hugr::persistent, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent.rs:1
mod hugr_core::hugr::persistent::walker, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker.rs:1
mod hugr_core::hugr::persistent::serial, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent.rs:763

--- failure struct_missing: pub struct removed or renamed ---

Description:
A publicly-visible struct cannot be imported by its prior path. A `pub use` may have been removed, or the struct itself may have been renamed or removed entirely.
      ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
     impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.41.0/src/lints/struct_missing.ron

Failed in:
struct hugr_core::hugr::persistent::serial::SerialCommitStateSpace, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/state_space/serial.rs:54
struct hugr_core::hugr::persistent::walker::Walker, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker.rs:87
struct hugr_core::hugr::persistent::Walker, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker.rs:87
struct hugr_core::hugr::persistent::PatchNode, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/state_space.rs:28
struct hugr_core::hugr::persistent::PointerEqResolver, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/resolver.rs:11
struct hugr_core::hugr::persistent::PersistentHugr, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent.rs:268
struct hugr_core::hugr::persistent::CommitStateSpace, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/state_space.rs:64
struct hugr_core::hugr::persistent::Commit, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent.rs:105
struct hugr_core::hugr::persistent::walker::PinnedWire, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker/pinned.rs:30
struct hugr_core::hugr::persistent::PinnedWire, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/persistent/walker/pinned.rs:30

[lmondada]

This PR contains breaking changes to the public Rust API.

All breaking changes are within the hugr::persistent directory. This module has never been released yet, so the changes are not breaking.

[lmondada]

After the patch release, this PR is now breaking. Adjusted it accordingly (but somehow the CI check is still failing, not sure why...).