create Alert.tsx and Alert.web.tsx and replace uses (#513)

src/view/com/util/Alert.tsx

@@ -0,0 +1 @@
+export {Alert} from 'react-native'

src/view/com/util/Alert.web.tsx

@@ -0,0 +1,23 @@
+import {AlertButton, AlertStatic} from 'react-native'
+
+class WebAlert implements Pick<AlertStatic, 'alert'> {
+  public alert(title: string, message?: string, buttons?: AlertButton[]): void {
+    if (buttons === undefined || buttons.length === 0) {
+      window.alert([title, message].filter(Boolean).join('\n'))
+      return
+    }
+
+    const result = window.confirm([title, message].filter(Boolean).join('\n'))
+
+    if (result === true) {
+      const confirm = buttons.find(({style}) => style !== 'cancel')
+      confirm?.onPress?.()
+      return
+    }
+
+    const cancel = buttons.find(({style}) => style === 'cancel')
+    cancel?.onPress?.()
+  }
+}
+
+export const Alert = new WebAlert()