Transform on devices and update insert

[rmoyard]

Description of the Change:

• Transforms can now be added to the preprocessing of device. dev = transform(dev)
• Insert is updated to the new transform system

Benefits:

Possible Drawbacks:
Default mixed is not a new generation device, the main use cases of applying insert on a device is for default mixed (adding noise).

• Add a special patch in transform dispatcher in the case of default mixed (to be removed in the future)

Related GitHub Issues:

[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

All modified lines are covered by tests ✅

Comparison is base (eafabe4) 99.65% compared to head (cae0fbc) 99.65%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4667   +/-   ##
=======================================
  Coverage   99.65%   99.65%           
=======================================
  Files         376      376           
  Lines       33678    33702   +24     
=======================================
+ Hits        33561    33585   +24     
  Misses        117      117           

Files	Coverage Δ
pennylane/transforms/core/transform_dispatcher.py	100.00% <100.00%> (ø)
pennylane/transforms/insert_ops.py	100.00% <100.00%> (ø)
pennylane/transforms/qfunc_transforms.py	90.00% <ø> (-3.16%)	⬇️

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[rmoyard]

[sc-43680]

[albi3ro]

Looks like we've removed some test coverage from qfunc_transform, but I'm fine with overriding that with in this case. qfunc_transform is slated for deprecation, and its the fault of qfunc_transform for not having proper unit tests.

Changelog and unit test for qml.Device, and I'd be happy to approve :)

[timmysilv]

changes look good, just some little comments.

i don't remember if we had already changed some transforms in the last release, but will we need to announce the breaking changes re: how to decorate a qnode, particularly with @partial?

[rmoyard]

@timmysilv I will update the transforms changelog during feature freeze to make sure all details are covered such as the @partial

[albi3ro]

👍 🚀

[timmysilv]

I'd like to allow for adding transforms to the front (rather than the back) of a program like this, but we can do that in another PR. For example, it would be useful if you want to decompose operators in a custom way before the device decomposition occurs (see what is being done in #4646 - it can't use this until support is added).