Add new .overflow-x, .overflow-y, and object-fit utilities

Overflow utilities are self-explanatory.

The object-fit property is used to specify how an `<img>` or `<video>` should be resized to fit its container. Offers a responsive alternative to using `background-image` for a resizable fill/fit image.

scss/_utilities.scss

@@ -22,6 +22,20 @@ $utilities: map-merge(
       )
     ),
     // scss-docs-end utils-float
+    // Object Fit utilities
+    // scss-docs-start utils-object-fit
+    "object-fit": (
+      responsive: true,
+      property: object-fit,
+      values: (
+        contain: contain,
+        cover: cover,
+        fill: fill,
+        scale: scale-down,
+        none: none,
+      )
+    ),
+    // scss-docs-end utils-object-fit
     // Opacity utilities
     // scss-docs-start utils-opacity
     "opacity": (
@@ -40,6 +54,14 @@ $utilities: map-merge(
       property: overflow,
       values: auto hidden visible scroll,
     ),
+    "overflow-x": (
+      property: overflow-x,
+      values: auto hidden visible scroll,
+    ),
+    "overflow-y": (
+      property: overflow-y,
+      values: auto hidden visible scroll,
+    ),
     // scss-docs-end utils-overflow
     // scss-docs-start utils-display
     "display": (