replace leading _ for private symbols with keyword hide

tree-sitter-brolang/test/corpus/syntax.txt

@@ -4,6 +4,16 @@ Core syntax
 
 io :: import "@std/io"
 
+hide private_value :: 1
+
+hide private_counter i32 = 0
+
+hide Private :: opaque
+
+hide private_sum func(a, b i32) i32 {
+	return a + b
+}
+
 Status :: enum {
 	ok
 	bad
@@ -30,6 +40,38 @@ sum func(a, b i32) i32 ! Status {
     (identifier)
     (string
       (string_content)))
+  (global_constant_declaration
+    (identifier)
+    (expression
+      (integer)))
+  (global_variable_declaration
+    (identifier)
+    (type
+      (builtin_type))
+    (expression
+      (integer)))
+  (type_declaration
+    (identifier)
+    (opaque_type))
+  (function_declaration
+    (identifier)
+    (parameter_list
+      (parameter
+        (identifier)
+        (identifier)
+        (type
+          (builtin_type))))
+    (type
+      (builtin_type))
+    (block
+      (statement
+        (return_statement
+          (expression
+            (binary_expression
+              (expression
+                (identifier))
+              (expression
+                (identifier))))))))
   (type_declaration
     (identifier)
     (enum_type

tree-sitter-brolang/test/highlight/intrinsics.bro

@@ -1,7 +1,10 @@
+hide helper func() void {}
+# <- keyword
+
 main func() void {
 	_ = sizeof!(i32)
 #	    ^^^^^^ function.builtin
-#	          ^ operator
+#	         ^ operator
 	_ = sizeof(i32)
 #	    ^^^^^^ function
 }