remove inverse support; add adjoint support; state-prep op cleanup

[timmysilv]

As the title says. op.inv() and op.inverse are removed from Operators in PennyLane 0.29, so this plugin needs updating accordingly. To summarize how I do it:

• All natively supported ops/obs are in a dict called _base_op/obs_map
• I dynamically copy the list, surrounding the names with Adjoint(...) (if the op exists and isn't already a natively supported adjoint op) and call the _op/obs_map. They're separate because the QSim devices did not support inverse ops so this will make it easy to preserve that assumption.
• The ops/obs list exposed to the pennylane supports_op/obs method now includes those Adjoint(...) ops/obs. No custom device.capabilities["supports_inverse_operation"] changes are needed because adjoint op names will be in the dict (rather than a hidden .inv property)
• The qsim(h) devices only expose the base ops (ie. without the Adjoint counterparts) to the pennylane supports_obs/ops thanks to the dict separation described above

The plugin also did lots of custom handling of StatePrep operators that will now be handled by the operators themselves, so I have removed that code. The custom handling had its own errors so tests were failing as they were, which is why I changed them in this PR. Both this and the inverse changes should happen in the same PR to update to the latest pennylane without breaking anything.

Note that because StatePrep.state_vector did not exist before PL 0.29, the version in setup.py will need to be bumped before this plugin is released.

[codecov]

Codecov Report

Merging #130 (ce6ccc3) into master (4c09d20) will decrease coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #130      +/-   ##
==========================================
- Coverage   99.23%   99.14%   -0.09%     
==========================================
  Files           8        8              
  Lines         392      352      -40     
==========================================
- Hits          389      349      -40     
  Misses          3        3              

Impacted Files	Coverage Δ
pennylane_cirq/pasqal_device.py	100.00% <ø> (ø)
pennylane_cirq/cirq_device.py	98.96% <100.00%> (-0.07%)	⬇️
pennylane_cirq/cirq_operation.py	100.00% <100.00%> (ø)
pennylane_cirq/qsim_device.py	96.87% <100.00%> (ø)
pennylane_cirq/simulator_device.py	100.00% <100.00%> (ø)

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[timmysilv]

[sc-33452]

[AlbertMitjans]

Amazing job! Left some comments, but it is good to go 💯 🔥

[lillian542]

Looks good to me!