filter clause with where <literal>=<literal> or <identifier>=<identifier> fail or are slow

[jadami10]

Queries with filter where 1=1 will fail. Several of the optimizers hit a null pointer exception. I tried tracking these down, but kept hitting ever more complex null pointer issues.

Queries with filter where "colA" = "colA" work correctly, but for expensive queries, these end up taking almost twice as long.

While this is quite a weird edge case, we see it where users are passing a string query between functions. They start the query with where A=A so they can keep appending filters after that without need to know if there was already a filter.

[Jackie-Jiang]

The reason why where colA = colA is slow is because it will be converted to where colA - colA = 0, which involves transform.
One solution is to remove the equality predicate when the LHS and RHS are the same.