added gradient shaders to all primatives

primatives/trapezoid.cpp

@@ -74,6 +74,13 @@ namespace UwU {
           }
           return;
 
+        } else if (shader.shaderType == BUFFER) {
+          for (uint16_t i = 0; i < height; i++) {
+            for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
+              buffer.drawPixel(x, i + y0, ShaderMethods::buffer(shader.u0, shader.v0, shader.buffer, x, i + y0));
+            }
+          }
+          return;
         }
         return;
       }