feat: Add experimental rewrite of go2rtc live provider (MSE/WebRTC/MP4/MJPEG) (#2580)

- Closes #2556
- Closes #2450

**Key intended features:**
 - go2rtc compatible
- 100% test coverage to significantly improve ability to test, maintain
and work around browser weirdnesses (e.g. Safari).
 - Written from the ground up in the style of the rest of the project.

**To use:**
 - Change `live_provider` from `go2rtc` to `go2rtc-experimental`.

tests/components-lib/notification/media.test.ts

@@ -0,0 +1,84 @@
+import { describe, expect, it } from 'vitest';
+
+import { createMediaNotification } from '../../../src/components-lib/notification/media';
+
+describe('createMediaNotification', () => {
+  it('should put the title and icon in the heading', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'Streaming server error',
+    });
+    expect(notification.heading).toEqual({
+      icon: 'mdi:alert-circle',
+      text: 'Streaming server error',
+    });
+  });
+
+  it('should default the icon to a generic alert icon', () => {
+    const notification = createMediaNotification({
+      title: 'Streaming server error',
+    });
+    expect(notification.heading?.icon).toBe('mdi:alert-circle');
+  });
+
+  it('should append the camera title to the heading', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'Streaming server error',
+      targetTitle: 'Front Door',
+    });
+    expect(notification.heading?.text).toBe('Streaming server error: Front Door');
+  });
+
+  it('should show the detail as the body', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'Configuration error',
+      detail: 'No endpoint',
+    });
+    expect(notification.body?.text).toBe('No endpoint');
+  });
+
+  it('should omit the body without a detail', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'X',
+    });
+    expect(notification.body).toBeUndefined();
+  });
+
+  it('should include the troubleshooting link', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'X',
+    });
+    expect(notification.link?.title).toBe('Check troubleshooting');
+    expect(notification.link?.url).toBeTruthy();
+  });
+
+  it('should omit the troubleshooting link when troubleshooting is false', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'X',
+      troubleshooting: false,
+    });
+    expect(notification.link).toBeUndefined();
+  });
+
+  it('should show a spinner by default', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'X',
+    });
+    expect(notification.in_progress).toBe(true);
+  });
+
+  it('should omit the spinner when not retrying', () => {
+    const notification = createMediaNotification({
+      icon: 'mdi:alert-circle',
+      title: 'X',
+      inProgress: false,
+    });
+    expect(notification.in_progress).toBeUndefined();
+  });
+});