docs: add Empty screen as playground (#2517)

# Summary

Create Empty screen with blank svg in example app as playground
Additionally add FeDropShadow icon as i forgot about it.

apps/common/example/examples/Empty.tsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import {Rect, Svg} from 'react-native-svg';
+
+function EmptyExample() {
+  return <Svg height="400" width="400"></Svg>;
+}
+EmptyExample.title = '';
+
+const icon = (
+  <Svg height="30" width="30" viewBox="0 0 20 20">
+    <Rect x="0" y="0" width="20" height="20" fill="none" stroke="black" />
+  </Svg>
+);
+const samples = [EmptyExample];
+
+export {icon, samples};

apps/common/example/examples/Filters/FeDropShadow.tsx

@@ -1,12 +1,5 @@
 import React from 'react';
-import {
-  Circle,
-  FeDropShadow,
-  FeFlood,
-  Filter,
-  Rect,
-  Svg,
-} from 'react-native-svg';
+import {Circle, FeDropShadow, Filter, Svg} from 'react-native-svg';
 
 BasicMDN.title = 'Basic MDN example';
 function BasicMDN() {
@@ -35,23 +28,17 @@ function BasicMDN() {
 }
 
 const icon = (
-  <Svg height="30" width="30" viewBox="0 0 140 140">
-    <Filter
-      id="floodFilterIcon"
-      x="50%"
-      filterUnits="userSpaceOnUse"
-      primitiveUnits="userSpaceOnUse">
-      <FeFlood
-        y="-10%"
-        x="10%"
-        width="50%"
-        height="50%"
-        floodColor="yellow"
-        floodOpacity="0.5"
-      />
+  <Svg height="30" width="30" viewBox="0 0 100 100">
+    <Filter id="dropShadowIcon" x="-1" width="3" y="-1" height="3">
+      <FeDropShadow dx="3" dy="3" stdDeviation="2" floodOpacity="0.7" />
     </Filter>
-    <Rect x="0" y="0" width="100" height="100" fill="blue" />
-    <Circle cx="50" cy="50" r="40" filter="url(#floodFilterIcon)" />
+    <Circle
+      cx="50"
+      cy="50"
+      r="30"
+      fill="lightblue"
+      filter="url(#dropShadowIcon)"
+    />
   </Svg>
 );
 const samples = [BasicMDN];

apps/common/example/examples/index.tsx

@@ -1,5 +1,6 @@
 import * as Circle from './Circle';
 import * as Clipping from './Clipping';
+import * as Empty from './Empty';
 import * as Ellipse from './Ellipse';
 import * as G from './G';
 import * as Gradients from './Gradients';
@@ -21,6 +22,7 @@ import * as TouchEvents from './TouchEvents';
 import * as Transforms from './Transforms';
 
 export const examples = {
+  Empty,
   Svg,
   Rect,
   Circle,