Fix Switch component accessibility role (#26899)

Summary:
`accessibilityRole` communicates the purpose of a component to the user of assistive technology. It needs to have the correct value for it to be fully utilized.

Switch component has `accessibilityRole` of a `button` instead of `switch` on default. Change the component default role to `switch`.

## Changelog

[General] [Fixed] - Change default `accessibilityRole` of Switch component from `button` to `switch`
Pull Request resolved: #26899

Test Plan:
- All unit test passed
- On Switch component, it's supposed to have `switch` like element type on both platform. (`XCUIElementTypeSwitch` on iOS)

fix [https://github.com/facebook/react-native/issues/26873](https://github.com/facebook/react-native/issues/26873)

Reviewed By: yungsters

Differential Revision: D18002755

Pulled By: mdvacca

fbshipit-source-id: 60446f94b23f8355f954805fb4dc08c89d08e492

Libraries/Components/Switch/Switch.js

@@ -156,7 +156,7 @@ class Switch extends React.Component<Props> {
         <AndroidSwitchNativeComponent
           {...props}
           {...platformProps}
-          accessibilityRole={props.accessibilityRole ?? 'button'}
+          accessibilityRole={props.accessibilityRole ?? 'switch'}
           onChange={this._handleChange}
           onResponderTerminationRequest={returnsFalse}
           onStartShouldSetResponder={returnsTrue}
@@ -189,7 +189,7 @@ class Switch extends React.Component<Props> {
       <SwitchNativeComponent
         {...props}
         {...platformProps}
-        accessibilityRole={props.accessibilityRole ?? 'button'}
+        accessibilityRole={props.accessibilityRole ?? 'switch'}
         onChange={this._handleChange}
         onResponderTerminationRequest={returnsFalse}
         onStartShouldSetResponder={returnsTrue}