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/live/providers/go2rtc-experimental/utils/failure-reason.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest';
+
+import { mapFailureReasonToIssueReason } from '../../../../../../src/components-lib/live/providers/go2rtc-experimental/utils/failure-reason';
+
+describe('mapFailureReasonToIssueReason', () => {
+  it.each([
+    ['connect_timeout', 'not_loading'],
+    ['negotiation_timeout', 'not_loading'],
+    ['media_error', 'playback_error'],
+    ['buffer_overflow', 'playback_error'],
+    ['two_way_audio_error', 'two_way_audio_error'],
+    ['server_error', 'server_error'],
+    ['unsupported', 'unsupported'],
+  ] as const)('should map %s to the %s cause', (reason, expected) => {
+    expect(mapFailureReasonToIssueReason(reason)).toBe(expected);
+  });
+
+  it('should map a null reason to a generic playback error', () => {
+    expect(mapFailureReasonToIssueReason(null)).toBe('playback_error');
+  });
+});