Add type hints

[Ericgig]

Description
Added hints to mesolve, sesolve, result, Qobj, QobjEvo.

The aim is not to pass static type checker, but to help the user with hints:

• I added types to outside facing functions.
• I sometime used hints that do not match the real implementation. For example:
  • Qobj.__mul__ is typed to support product with scalar, not other Qobj, (for which __matmul__ should be used.)
  • e_ops are hinted to dict but also support single operator, list, tuple...
  • solver.options claim it return a dict not _SolverOptions (which is a subclass of dict.)
• I skipped the None type. (result.final_state type is Qobj event if it is None when not saved.)

I created alias types:

• QobjEvoLike: Stuff that can be made into a QobjEvo.
• CoefficientLike: Stuff that can be made into a Coefficient.
• LayerType: Can be understood as our data layer type. (A dynamically generated Literal could be better.)
  Maybe some alias for dimensions object could be useful?

Knowing that we have extension modules, I used numbers.Number for complex hoping it support jax or tensorflow's scalars. Also Any used in some place where other type support can be added such as Qobj.__init__.

Some of the type hint features I used were only added in python 3.10. We still tests with python 3.9, but it's old enough that we can remove it (according to spec-0000).

[coveralls]

coverage: 86.26% (+0.04%) from 86.22%
when pulling a8b95a9 on Ericgig:misc.type_hints
into 8ab189e on qutip:master.