Remix PWA Push Fix

[ShafSpecs]

Closes #271

This push aims to make sending notifications more streamlined, allowing you to send notifications whilst retaining errors. As well as a new utility function for filtering results:

for (const subscription of allSubscriptions) {
 const result = await sendNotifications({ ... })

 // returns an object of the following:
 type Result = {
    success: boolean;
    subscription: PushSubscription;
    statusCode: number;
    error?: undefined;
 } | {
    success: boolean;
    subscription: PushSubscription;
    error: string;
    statusCode?: undefined;
 })[]

 // using the new `getNotificationResults` util on `result`, we get an object of the following
  {
    successful: results.filter((r): r is NotificationResult & { success: true } => r.success),
    failed: results.filter((r): r is NotificationResult & { success: false } => !r.success),
    summary: {
      total: number,
      successCount: number,
      failureCount: number,
    },
  }
}