Summary:
Hi!
I found problem with accessibilityLabel on PickerAndroid.
There's no value in content-desc attribute while accessibilityLabel is correct.
I found that accessibilityLabel is not propagated into native components via
native props.
This PR brings accessibilityLabel for PickerAndroid.
Without this solution my appium tests fails, for example:
My code:
```jsx
<Picker
style={this.props.style}
selectedValue={this.props.value}
onValueChange={this.onChange}
disabled={this.props.disabled}
accessibilityLabel="select_wineType">
// Chilren
</Picker>
```
```sh
✖ Error: element (~select_wineType) still not visible after 5000ms
```
Because xml of this view is (look into content-desc of Spinner):
```xml
<android.widget.Spinner index="0" text="" class="android.widget.Spinner" package="com.hello_github" content-desc="" checkable="false" checked="false" clickable="true" enabled="true" focusable="true" focused="false" scrollable="true" long-clickable="false" password=
Closes https://github.com/facebook/react-native/pull/8873
Differential Revision: D3831691
Pulled By: spicyj
fbshipit-source-id: a494f22cb8be8cd6964981fe7ef7d9ff3773bcce
efd8b10135