Bug 69031

The idea is that to attempt a regex match. When there is a regex match, use the exact match and count additions and removals and do a diff to determine if it the pattern is a match. This allows one to have a pattern like this: more_in_code: r'RefCountedThreadSafe<|RefCounted<' and then the pattern matches if the number of ThreadSafeRefCount< or RefCounted< increased in any file (even if one was replaced by the other). This is a simple way to do mimic an intraline diff and say that the an occurrence of a string is new (which is typically what people would want to see).