replace leading _ for private symbols with keyword hide

tree-sitter-brolang/grammar.js

@@ -51,6 +51,7 @@ module.exports = grammar({
     ),
 
     function_declaration: $ => seq(
+      optional('hide'),
       field('name', $.identifier),
       field('kind', choice('func', 'c_func')),
       field('parameters', $.parameter_list),
@@ -64,6 +65,7 @@ module.exports = grammar({
     ),
 
     type_declaration: $ => prec(1, seq(
+      optional('hide'),
       field('name', $.identifier),
       '::',
       repeat($._newline),
@@ -79,6 +81,7 @@ module.exports = grammar({
     )),
 
     global_constant_declaration: $ => seq(
+      optional('hide'),
       field('name', $.identifier),
       optional(field('type', $.type)),
       '::',
@@ -87,6 +90,7 @@ module.exports = grammar({
     ),
 
     global_variable_declaration: $ => seq(
+      optional('hide'),
       field('name', $.identifier),
       optional(field('type', $.type)),
       '=',