feat!: Remove RootCheckable

[cqc-alec]

Closes #2577 .

BREAKING CHANGE: Use RootChecked or HugrView instead of RootCheckable.

[codecov]

Codecov Report

❌ Patch coverage is 86.11111% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.54%. Comparing base (ecc8bf0) to head (3a81b25).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
hugr-core/src/hugr/views/sibling_subgraph.rs	90.90%	2 Missing ⚠️
hugr-passes/src/lib.rs	0.00%	2 Missing ⚠️
hugr-passes/src/nest_cfgs.rs	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2704   +/-   ##
=======================================
  Coverage   83.53%   83.54%           
=======================================
  Files         266      266           
  Lines       51718    51714    -4     
  Branches    47184    47180    -4     
=======================================
  Hits        43202    43202           
+ Misses       6136     6134    -2     
+ Partials     2380     2378    -2     

Flag	Coverage Δ
python	91.53% <ø> (ø)
rust	82.77% <86.11%> (+<0.01%)	⬆️

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[ss2165]

Ideally the try_new(..).unwrap() would be .expect("dfg root") etc.

[hugrbot]

This PR contains breaking changes to the public Rust API.

cargo-semver-checks summary

    Building hugr v0.24.3 (current)
     Built [  29.626s] (current)
   Parsing hugr v0.24.3 (current)
    Parsed [   0.004s] (current)
  Building hugr v0.24.3 (baseline)
     Built [  25.281s] (baseline)
   Parsing hugr v0.24.3 (baseline)
    Parsed [   0.004s] (baseline)
  Checking hugr v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.010s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  56.559s] hugr
  Building hugr-cli v0.24.3 (current)
     Built [  24.239s] (current)
   Parsing hugr-cli v0.24.3 (current)
    Parsed [   0.009s] (current)
  Building hugr-cli v0.24.3 (baseline)
     Built [  23.755s] (baseline)
   Parsing hugr-cli v0.24.3 (baseline)
    Parsed [   0.010s] (baseline)
  Checking hugr-cli v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.015s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  49.833s] hugr-cli
  Building hugr-core v0.24.3 (current)
     Built [  16.093s] (current)
   Parsing hugr-core v0.24.3 (current)
    Parsed [   0.075s] (current)
  Building hugr-core v0.24.3 (baseline)
     Built [  15.883s] (baseline)
   Parsing hugr-core v0.24.3 (baseline)
    Parsed [   0.075s] (baseline)
  Checking hugr-core v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.153s] 159 checks: 158 pass, 1 fail, 0 warn, 41 skip

--- failure trait_missing: pub trait removed or renamed ---

Description:
A publicly-visible trait cannot be imported by its prior path. A `pub use` may have been removed, or the trait 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/v0.45.0/src/lints/trait_missing.ron

Failed in:
trait hugr_core::hugr::views::RootCheckable, previously in file /home/runner/work/hugr/hugr/BASELINE_BRANCH/hugr-core/src/hugr/views/root_checked.rs:73

   Summary semver requires new major version: 1 major and 0 minor checks failed
  Finished [  33.320s] hugr-core
  Building hugr-llvm v0.24.3 (current)
     Built [  19.617s] (current)
   Parsing hugr-llvm v0.24.3 (current)
    Parsed [   0.011s] (current)
  Building hugr-llvm v0.24.3 (baseline)
     Built [  19.168s] (baseline)
   Parsing hugr-llvm v0.24.3 (baseline)
    Parsed [   0.011s] (baseline)
  Checking hugr-llvm v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.031s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  39.865s] hugr-llvm
  Building hugr-model v0.24.3 (current)
     Built [   4.837s] (current)
   Parsing hugr-model v0.24.3 (current)
    Parsed [   0.015s] (current)
  Building hugr-model v0.24.3 (baseline)
     Built [   4.722s] (baseline)
   Parsing hugr-model v0.24.3 (baseline)
    Parsed [   0.014s] (baseline)
  Checking hugr-model v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.025s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  10.309s] hugr-model
  Building hugr-passes v0.24.3 (current)
     Built [  19.796s] (current)
   Parsing hugr-passes v0.24.3 (current)
    Parsed [   0.024s] (current)
  Building hugr-passes v0.24.3 (baseline)
     Built [  20.026s] (baseline)
   Parsing hugr-passes v0.24.3 (baseline)
    Parsed [   0.023s] (baseline)
  Checking hugr-passes v0.24.3 -> v0.24.3 (assume minor change)
   Checked [   0.028s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  40.907s] hugr-passes
  Building hugr-persistent v0.3.4 (current)
     Built [  16.304s] (current)
   Parsing hugr-persistent v0.3.4 (current)
    Parsed [   0.007s] (current)
  Building hugr-persistent v0.3.4 (baseline)
     Built [  16.327s] (baseline)
   Parsing hugr-persistent v0.3.4 (baseline)
    Parsed [   0.007s] (baseline)
  Checking hugr-persistent v0.3.4 -> v0.3.4 (assume minor change)
   Checked [   0.011s] 159 checks: 159 pass, 41 skip
   Summary no semver update required
  Finished [  33.781s] hugr-persistent