consistent usages of `np.RandomState` in the code about monai

[wyli]

(cc @ericspod @john-zielke-snkeos follow-up of the discussions in #6854, self.R and RandomState is currently preferred over np.random.*, this ticket is to track the issue.
e.g. preferred usage:

MONAI/monai/data/synthetic.py

Line 65 in 8aabdc9

rs: np.random.RandomState = np.random.random.__self__ if random_state is None else random_state # type: ignore

)

[ericspod]

If we wanted to first change the usages of np.random.* to use a RandomState then migrate in the future to Generator we could do the following:

• Change the usage of np.random.* in transforms to use self.R. This will change some expected deterministic behaviour but would be more reproducible.
• In other places in core change routines to accept a RandomState object as an argument and use that, defaulting to np.random if none is provided. This would cover most use cases with minimal addition. @wyli 's code snippet is probably the technique to use for this.
• In apps/* and auto3dseg ask contributors what they would want to do, mentioning we're trying to tighten up the implementation with an eye to future migration.

We do need to have a more considered discussion about what to do about migration at some point, either we move to Generator or we do implement our own class to replace RandomState usage.