Implments display trait and add doc tests

Author: hapenia

godot-core/src/builtin/projection.rs

@@ -1008,20 +1008,3 @@ impl std::fmt::Display for Projection {
         )
     }
 }
-
-#[test]
-fn display_test() {
-    const TEST_DATA: [Vector4; 4] = [
-        Vector4::new(1.0, 2.5, 1.0, 0.5),
-        Vector4::new(0.0, 1.5, 2.0, 0.5),
-        Vector4::new(0.0, 0.0, 3.0, 2.5),
-        Vector4::new(3.0, 1.0, 4.0, 1.5),
-    ];
-    const EXPECTED_RESULT: &str = r"
-1, 0, 0, 3
-2.5, 1.5, 0, 1
-1, 2, 3, 4
-0.5, 0.5, 2.5, 1.5
-";
-    assert_eq!(format!("{}", Projection::new(TEST_DATA)), EXPECTED_RESULT)
-}