[BUG] REGEXP_REPLACE does not protect against columnar replace

[revans2]

Describe the bug
You can pass anything you want as the replacement to REGEXP_REPLACE, but it does not support columnar input, and it does not support a null literal either. In both cases you will get an exception. This is similar to #116 but I filed a separate issue because it is a separate operator, even though it has the same underlying implementation.

[kuhushukla]

Fixed via 35b3f07