LibGLSL: Add tests for GLSL parser

Author: https://github.com/Poseydon42
Commit: d160ff2f8d
Pull-request: https://github.com/SerenityOS/serenity/pull/20168
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/gmta ✅
Reviewed-by: https://github.com/sunverwerth
Reviewed-by: https://github.com/vkoskiv

Userland/Libraries/LibGLSL/Tests/parser/struct.ast

@@ -0,0 +1,7 @@
+TranslationUnit[0:0->3:1]
+  StructDeclaration[0:7->3:1]
+    foo
+    VariableDeclaration[2:4->3:0]
+      Type[2:4->2:6]
+        int
+      bar