fix!: don't parse unquoted predicate args specially

Before this change, a bare `_` identifier inside a predicate would be
tokenized as `"_"`. This change makes it so that all unquoted arguments
(which must be valid identifiers) are marked as `(identifier)`.

This is breaking because `"_"` can no longer be queried inside parameter
nodes.

Author: ribru17

grammar.js

@@ -66,7 +66,7 @@ module.exports = grammar({
       token.immediate('"'),
     ),
     string_content: $ => repeat1(choice(token.immediate(prec(PREC.STRING, /[^"\\\n]+/)), $.escape_sequence)),
-    parameters: $ => repeat1(choice($.capture, $.string, $._node_identifier)),
+    parameters: $ => repeat1(choice($.capture, $.string, $.identifier)),
     comment: _ => token(prec(PREC.COMMENT, seq(";", /.*/))),
     list: $ => seq("[", repeat1($.definition), "]", suffix($)),