Documentation and tests for cursor.callproc()

[Shai Berger]

This is a spin off #23546 -- actually, a requirement for that ticket.

Quoting my ​message to -developers on the subject (the thread trails off to discussions of higher-level interfaces, but the following seems to be in consensus):

For a very long time -- as far as I'm aware, forever -- we've had, in our cursor classes, a callproc() method that follows the callproc() definition of ​pep249; this allows database stored procedures to be called.

Recently [...] we found that

1. cursor.callproc() is not documented
2. cursor.callproc() is not tested (except for one Oracle-specific test that uses it to test something else)

Which means, essentially, that it is treated as an intenal API.

I see no reason that we shouldn't make it public.

[Michael Manfre]

Agreed. This should be documented and tested.

[Mariusz Felisiak]

I would like to resolve this issue, but it seems that we don't have appropriate place for cursor.callproc in the documentation. Any suggestions?

[Tim Graham]

Perhaps near the ​Connections and cursors section? Anyway, getting a draft of the content is most of the work; it can be moved if needed.

[GitHub <noreply@…>]

In 3189a93c:

Refs #23766 -- Added tests for CursorWrapper.callproc().

Thanks Tim Graham for the review.

[GitHub <noreply@…>]

In 660d5080:

Fixed #23766 -- Doc'd CursorWrapper.callproc().

Thanks Tim Graham for the review.

[Mariusz Felisiak <felisiak.mariusz@…>]

In fe51017e:

[1.11.x] Fixed #23766 -- Doc'd CursorWrapper.callproc().

Thanks Tim Graham for the review.
Backport of 660d50805b6788d592b4f1fae706b725baf0195c from master