feat(qsystem): native gateset decomposition improvements

[ss2165]

1. Fix CY decomposition Closes qsystem: incorrect cy decomposition #1058

Found using

from pytket import Circuit, OpType
from pytket.passes import AutoSquash


c = Circuit(2).CY(0, 1)
AutoRebase({OpType.PhasedX, OpType.Rz, OpType.ZZPhase}).apply(c)
AutoSquash({OpType.PhasedX, OpType.Rz}).apply(c)

[PhasedX(3, 1) q[0]; PhasedX(1.5, 1) q[1]; ZZPhase(0.5) q[0], q[1]; PhasedX(3, 0.5) q[0]; PhasedX(3.5, 1.5) q[1]; Rz(3.5) q[0]; Rz(2.5) q[1]; ]

2. Remove unnecessary PhasedX in build_cz

BEGIN_COMMIT_OVERRIDE
fix(qsystem): correct CY decomposition to hardware gateset

feat(qsystem): remove unecessary phasedx wrappers in CZ
END_COMMIT_OVERRIDE

[codecov]

Codecov Report

❌ Patch coverage is 14.28571% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.24%. Comparing base (f1ee0a4) to head (8c76709).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
tket-qsystem/src/extension/qsystem.rs	14.28%	0 Missing and 6 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1059      +/-   ##
==========================================
- Coverage   78.24%   78.24%   -0.01%     
==========================================
  Files         102      102              
  Lines       12785    12783       -2     
  Branches    12506    12504       -2     
==========================================
- Hits        10004    10002       -2     
  Misses       2125     2125              
  Partials      656      656              

Flag	Coverage Δ
rust	78.18% <14.28%> (-0.01%)	⬇️

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[aborgna-q]

Ouch.

Any way we could test these?

[ss2165]

theorem provers? execution dependency on selene? run pytket and compare?

[ss2165]

I will add a test in selene (passing locally)