Fix expression grammar to work with boolean functions

[SteveL-MSFT]

PR Summary

The grammar didn't allow for functions true() and false() and only expected boolean arguments true and false so this resulted in a parsing error. Fix is to update the grammar with precedence for functions and booleans (in that order) so that true() and false() will be accepted as function names and not treated as booleans and thus invalidating the rest of the expression.

Some of the invalid tests needed to be updated, but all still result in an error as expected.

PR Context

Fix #1136

[Gijsreyn]

LGTM!

[andyleejordan]

I think this LGTM though I'm not a tree-sitter expert and can't explain exactly how this automatically resolves true() and false() to true and false. Per the tests, it does. My guess is that it's a recursive evaluation of the $._booleanLiteral when it's the functionName.

[SteveL-MSFT]

I think this LGTM though I'm not a tree-sitter expert and can't explain exactly how this automatically resolves true() and false() to true and false. Per the tests, it does. My guess is that it's a recursive evaluation of the $._booleanLiteral when it's the functionName.

The main change in the grammar to fix this is to ensure that true and false are both booleans as parameters to functions, but also as true() and false() functions. Without this change (even if you set precedence), it would match to the boolean first because it's an exact match compared to the regex and thus never match as a function. In this case, we have explicitly added true and false as possible function names (in addition to the regex) so that it can be matched and the precedence (higher number is higher precedence) means it'll be evaluated first as a potential function name before identifying it as a boolean value. This behavior is specific to tree-sitter generated parser. Thanks for the extra set of eyes!