Range stridability algebra

[vasslitvinov]

This issues proposes user-facing functions to do the following:

• given multiple strides values, what strides value can accommodate all strides allowed by all these strides? For example, (one, positive) → positive; (one, negOne) → any; etc.
• given two strides values, what strides value can accommodate all products of the two strides allowed by these two strides? For example, (one, positive) → positive; (one, negOne) → negOne; etc.

These queries may arise in code generic over ranges or domains, for example in domain map implementations. Prior to the conversion range.stridable → ranges.strides started in #22441, our domain maps and internal modules defined multiple copies of proc anyStridable that answered both of the above queries at the same time.

Currently there are undocumented functions chpl_strideUnion() and chpl_strideProduct() that answer the above queries. This issue proposes to document them and make available to users and to giving them non-chpl_ names.