Optimization for predicates involving contains

[diana-qing]

This PR provides some optimizations when processing multiple predicates (where at least one of the predicates uses a contains operator) based on whether the predicates are mutually exclusive or have a parent-child relationship.

Given 2 predicates self and pred:

Mutual exclusivity rules:
self.op is = and pred.op is contains: mutually exclusive iff self.value doesn't contain pred.value

self.op is contains and pred.op is contains: generally not mutually exclusive

self.op is != and pred.op is contains: generally not mutually exclusive

self.op is re and pred.op is contains: generally not mutually exclusive/out of scope since contains can be understood as a regex with wildcards on both sides

Parent-child rules: (parent op must be contains, child op can be = or contains)
If pred.op is contains and self.op is = or self.op is contains, self is a child of pred iff self.value contains pred.value