fix: set default strokeWidth to 1 on android (#2269)

# Summary

According to [MDN
Docs](https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/stroke-width),
when `strokeWidth` is not provided, the default value should be set to
`1`.

On android, when we update the `strokeWidth` prop to `undefined` it was
mistakenly converted to `0` by `SVGLength`.

Fixes #2266 

## Test Plan

Test available in `TestsExample/Test2266` 

### What are the steps to reproduce (after prerequisites)?

* Run `TestsExample` app
* Replace `ColorTest` with `Test2266` in `App.js`

TestsExample/App.js

@@ -11,6 +11,7 @@ import PointerEventsBoxNone from './src/PointerEventsBoxNone';
 import Test2071 from './src/Test2071';
 import Test2089 from './src/Test2089';
 import Test2196 from './src/Test2196';
+import Test2266 from './src/Test2266';
 
 export default function App() {
   return <ColorTest />;

TestsExample/src/Test2266.tsx

@@ -0,0 +1,27 @@
+import React, {useState} from 'react';
+import {Button, View} from 'react-native';
+import {Circle, Svg} from 'react-native-svg';
+
+export default () => {
+  const [strokeWidth, setStrokeWidth] = useState<undefined | number>(undefined);
+  return (
+    <View>
+      <Svg viewBox="0 0 30 10" width={400} height={200}>
+        <Circle cx="5" cy="5" r="3" stroke="green" />
+        <Circle cx="15" cy="5" r="3" stroke="green" strokeWidth="3" />
+        <Circle cx="25" cy="5" r="3" stroke="green" strokeWidth="2%" />
+      </Svg>
+      <Button
+        title="stroke: undefined"
+        onPress={() => setStrokeWidth(undefined)}
+      />
+      <Button title="stroke: 0" onPress={() => setStrokeWidth(0)} />
+      <Button title="stroke: 1" onPress={() => setStrokeWidth(1)} />
+      <Button title="stroke: 2" onPress={() => setStrokeWidth(2)} />
+      <Svg viewBox="0 0 30 10" width={400} height={200}>
+        <Circle cx="5" cy="5" r="3" stroke="green" strokeWidth={strokeWidth} />
+        <Circle cx="10" cy="5" r="3" stroke="green" />
+      </Svg>
+    </View>
+  );
+};

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

@@ -273,7 +273,7 @@ public void setStrokeDashoffset(float strokeDashoffset) {
   }
 
   public void setStrokeWidth(Dynamic strokeWidth) {
-    this.strokeWidth = SVGLength.from(strokeWidth);
+    this.strokeWidth = strokeWidth.isNull() ? new SVGLength(1) : SVGLength.from(strokeWidth);
     invalidate();
   }