Fix #1345: opacity does not work with currentColor on Android (#2080)

I implemented this by multiplying the alpha of the currentColor by the opacity when setting a currentColor brush.

Co-authored-by: Wojciech Lewicki <wojciech.lewicki@swmansion.com>

TestsExample/App.js

@@ -6,6 +6,7 @@ import Test1374 from './src/Test1374';
 import Test1718 from './src/Test1718';
 import Test1813 from './src/Test1813';
 import Test1845 from './src/Test1845';
+import Test2080 from './src/Test2080';
 import PointerEventsBoxNone from './src/PointerEventsBoxNone';
 
 export default function App() {

TestsExample/src/Test2080.tsx

@@ -0,0 +1,17 @@
+import * as React from 'react';
+import { View } from 'react-native';
+import Svg, {Rect} from 'react-native-svg';
+
+export default function App() {
+
+  return (
+    <View style={{flex: 1}}>
+      <Svg width="100%" height="100%" viewBox="0 0 56 56" color="red">
+          <Rect width="20" height="20" rx="4" fill="currentColor" opacity={0.2} />
+          <Rect x="0" y="25" width="20" height="20" rx="4" fill="red" opacity={0.2} />
+          <Rect x="25" y="0" width="20" height="20" rx="4" fill="red" />
+          <Rect x="25" y="25" width="20" height="20" rx="4" fill="blue" fillOpacity="0.2"  />
+        </Svg>
+      </View>
+  );
+}

android/src/main/java/com/horcrux/svg/RenderableView.java

@@ -570,8 +570,10 @@ public abstract class RenderableView extends VirtualView implements ReactHitSlop
         }
       case 2:
         {
-          int brush = getSvgView().mTintColor;
+          int color = getSvgView().mTintColor;
-          paint.setColor(brush);
+          int alpha = color >>> 24;
+          alpha = Math.round((float) alpha * opacity);
+          paint.setColor(alpha << 24 | (color & 0x00ffffff));
           break;
         }
       case 3: