Return boolean literal when simplifying AND and OR filters

[angelamayxie]

fixes dolthub/dolt#10243

Previously, if one of the children of an AND or OR expression was a literal that evaluated to false or true (respectively), we would return the child. However, this caused a typing issue since AND and OR are booleans while its children can be of any type. Take the expression 19 or 's' for example; the left child 19 evaluates to true, making the expression true every time, but returning the left child 19 as a simplification would be incorrect since we would want the expression to simplify to a boolean true, not the number 19.

Now, instead of returning the child that determines the result of an AND or OR expression, we return the boolean value that the expression results to.

[jycor]

LGTM