Deprecate `many`/`match_many` option from the argument processor

[SamirDroubi]

The many option currently exists for the StmtCursorA, ExprCursorA, and BlockCursorA processors. However, it is virtually not used anywhere in our code except for two places, which themsevles can be deprecated.

First usage:

@sched_op([ExprCursorA(many=True), NameA, BoolA])
def bind_expr(proc, expr_cursors, new_name, cse=False):

When we specify cse=True, then we would perform CSE on all expressions that match the pattern. Otherwise, it will simply bind the first expressions that matches the pattern. I think generally implementing this as ListOrElemA(NewExprA)) would make more sense. If I want to replicate the old behavior, I can simply call Procedure::find(pat, many=True) and pass that as an argument.

Second usage:

@sched_op([ExprCursorA(many=True)])
def commute_expr(proc, expr_cursors):

This simply loops through all the cursors and commutes each one. It can be changed to work for exactly one expression and replicate the looping functionality using high-order operations.