Add wires to device api

[timmysilv]

Context:
The new device API does not currently accept wires, but users (and thousands, if not millions of tests) have grown to expect it.

Description of the Change:

• Add device wires as an optional property to the new device API. If nothing is given, dev.wires will be None

Benefits:

• The new device API is more user-friendly
• It will be much much easier to port tests to the new default.qubit
• This will probably be needed for qml.state() + DQ2 improvements coming soon

Possible Drawbacks:
N/A

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit doc/releases/changelog-dev.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (a6dc1be) 99.66% compared to head (e850d14) 99.66%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4538   +/-   ##
=======================================
  Coverage   99.66%   99.66%           
=======================================
  Files         376      376           
  Lines       33060    33070   +10     
=======================================
+ Hits        32950    32960   +10     
  Misses        110      110           

Files Changed	Coverage Δ
pennylane/devices/experimental/default_qubit_2.py	100.00% <100.00%> (ø)
pennylane/devices/experimental/device_api.py	98.46% <100.00%> (+0.27%)	⬆️

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[timmysilv]

I think codecov is comparing against the wrong base?

[lillian542]

Looks good to me!

[albi3ro]

All things old are new again. But at least optional 🤷