Put removal of '!' as a synonym for 'NOT' on a keyword level under a config

Recently we dissolved the lexer equivalence between '!' and 'NOT'.
! is a prefix operator and a synonym for NOT only in that case.
But NOT is used in many more cases in the grammar.
Given that there are a handful of known scenearios where users have exploited the undocumented loophole it's best to add a config.
Usage found so far is:

`c1 ! IN(1, 2)`
`c1 ! BETWEEN 1 AND 2`
`c1 ! LIKE 'a%'`

 But there are worse cases:
c1 IS ! NULL
CREATE TABLE T(c1 INT ! NULL)
or even
CREATE TABLE IF ! EXISTS T(c1 INT)