improve builtins shape and ndim; add math.get_deep_interface

[timmysilv]

Context:
Sometimes people do things on lists like [jnp.array(1.1), jnp.array(2.2)] and autoray thinks the interface is builtins. This happens a lot with Hamiltonian.coeffs. I'm here to help autoray.

Description of the Change:

• Add qml.math.get_deep_interface to extract out the interface from one of those (arbitrarily) deeply nested lists of lists, or tuples of tuples. Note that I assume the struct isn't ragged, because if you're asking for the interface, you're probably about to cast the whole list and that can fail if it needs to
• Change the builtins implementation for ndim and shape to check if it's a nested type containing a different interface. Then, cast to that interface and use its implementation for ndim/shape

Benefits:
We can get the ndim/shape of ugly nested things, and the helper function might be generally helpful elsewhere

Possible Drawbacks:
None!!!

Related GitHub Issues:
Fixes #4601

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (057c776) 99.63% compared to head (fb5340b) 99.63%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4603   +/-   ##
=======================================
  Coverage   99.63%   99.63%           
=======================================
  Files         376      376           
  Lines       33649    33665   +16     
=======================================
+ Hits        33525    33541   +16     
  Misses        124      124           

Files	Coverage Δ
pennylane/math/__init__.py	100.00% <ø> (ø)
pennylane/math/single_dispatch.py	99.47% <100.00%> (+0.01%)	⬆️
pennylane/math/utils.py	99.18% <100.00%> (+0.04%)	⬆️

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