Display WiKit Input placeholder correct color for v2.x release (#626)

* Display WiKit Input placeholder correct color (#624)

Bug: T312633

* Emtpy commit for CI

Author: guergana

tokens/properties/alias.json

@@ -380,6 +380,9 @@
     "opacity": {
         "overlay": {
             "value": "{opacity.65.value}"
+        },
+        "base": {
+            "value": "{opacity.100.value}"
         }
     },
     "dimension": {

tokens/properties/components/Input.json

@@ -45,6 +45,9 @@
             },
             "color": {
                 "value": "{font.color.subtle.value}"
+            },
+            "opacity": {
+                "value": "{opacity.base.value}"
             }
         },
         "disabled": {

vue-components/src/components/Input.vue

@@ -78,6 +78,11 @@ export default Vue.extend( {
 		outline: none;
 	}
 
+	&::placeholder {
+		color: $wikit-Input-placeholder-color;
+		opacity: $wikit-Input-placeholder-opacity;
+	}
+
 	&:not(&--error):not(&--warning) {
 		&:not(:disabled) {
 			&:hover {