Add additional simplification rules #1406

As pointed out by @xudong963 on #1376, there are several other rewrite rules we could add following the pattern in simplify:

A AND !(A) --> false (if A is not nullable)

Note that if A is null (or some expresson that could be null), then A AND !(A) is NULL

Similarly,

A * 0 --> 0 (if A is not nullable)

The "is nullable" bit is somewhat tricky -- and to be honest I am not sure our current code handles all such cases correctly either.