[improvement] add Picker prop mixin (#2191)

packages/mixins/picker.js

@@ -0,0 +1,21 @@
+/**
+ * Common Picker Props
+ */
+
+export default {
+  props: {
+    title: String,
+    loading: Boolean,
+    showToolbar: Boolean,
+    cancelButtonText: String,
+    confirmButtonText: String,
+    visibleItemCount: {
+      type: Number,
+      default: 5
+    },
+    itemHeight: {
+      type: Number,
+      default: 44
+    }
+  }
+};