Add connection tester failure pixels (#881)

Task/Issue URL: https://app.asana.com/0/1206580121312550/1207743877093953/f

iOS PR: duckduckgo/iOS#3049
macOS PR: duckduckgo/macos-browser#2948

What kind of version bump will this require?: Patch

## Description

Adds pixels to track connection tester failures and recovery.  These should give us a better idea about how users are faring.

Sources/NetworkProtection/Diagnostics/NetworkProtectionConnectionTester.swift

@@ -32,7 +32,7 @@ import Common
 final class NetworkProtectionConnectionTester {
     enum Result {
         case connected
-        case reconnected
+        case reconnected(failureCount: Int)
         case disconnected(failureCount: Int)
     }
 
@@ -267,9 +267,8 @@ final class NetworkProtectionConnectionTester {
         if failureCount == 0 {
             resultHandler(.connected)
         } else if failureCount > 0 {
+            resultHandler(.reconnected(failureCount: failureCount))
             failureCount = 0
-
-            resultHandler(.reconnected)
         }
     }
 

Sources/NetworkProtection/PacketTunnelProvider.swift

@@ -32,6 +32,7 @@ open class PacketTunnelProvider: NEPacketTunnelProvider {
 
     public enum Event {
         case userBecameActive
+        case connectionTesterStatusChange(_ status: ConnectionTesterStatus, server: String)
         case reportConnectionAttempt(attempt: ConnectionAttempt)
         case tunnelStartAttempt(_ step: TunnelStartAttemptStep)
         case tunnelStopAttempt(_ step: TunnelStopAttemptStep)
@@ -64,6 +65,16 @@ open class PacketTunnelProvider: NEPacketTunnelProvider {
         case failure
     }
 
+    public enum ConnectionTesterStatus {
+        case failed(duration: Duration)
+        case recovered(duration: Duration, failureCount: Int)
+
+        public enum Duration: String {
+            case immediate
+            case extended
+        }
+    }
+
     // MARK: - Error Handling
 
     public enum TunnelError: LocalizedError, CustomNSError, SilentErrorConvertible {
@@ -309,23 +320,50 @@ open class PacketTunnelProvider: NEPacketTunnelProvider {
 
     // MARK: - Connection tester
 
+    private static let connectionTesterExtendedFailuresCount = 8
     private var isConnectionTesterEnabled: Bool = true
 
     @MainActor
     private lazy var connectionTester: NetworkProtectionConnectionTester = {
         NetworkProtectionConnectionTester(timerQueue: timerQueue, log: .networkProtectionConnectionTesterLog) { @MainActor [weak self] result in
             guard let self else { return }
 
+            let serverName = lastSelectedServerInfo?.name ?? "Unknown"
+
             switch result {
             case .connected:
                 self.tunnelHealth.isHavingConnectivityIssues = false
                 self.updateBandwidthAnalyzerAndRekeyIfExpired()
 
-            case .reconnected:
+            case .reconnected(let failureCount):
+                providerEvents.fire(
+                    .connectionTesterStatusChange(
+                        .recovered(duration: .immediate, failureCount: failureCount),
+                        server: serverName))
+
+                if failureCount >= Self.connectionTesterExtendedFailuresCount {
+                    providerEvents.fire(
+                        .connectionTesterStatusChange(
+                            .recovered(duration: .extended, failureCount: failureCount),
+                            server: serverName))
+                }
+
                 self.tunnelHealth.isHavingConnectivityIssues = false
                 self.updateBandwidthAnalyzerAndRekeyIfExpired()
 
             case .disconnected(let failureCount):
+                if failureCount == 1 {
+                    providerEvents.fire(
+                        .connectionTesterStatusChange(
+                            .failed(duration: .immediate),
+                            server: serverName))
+                } else if failureCount == 8 {
+                    providerEvents.fire(
+                        .connectionTesterStatusChange(
+                            .failed(duration: .extended),
+                            server: serverName))
+                }
+
                 self.tunnelHealth.isHavingConnectivityIssues = true
                 self.bandwidthAnalyzer.reset()
             }

Sources/PixelKit/PixelKit+Parameters.swift

@@ -21,6 +21,7 @@ import Foundation
 public extension PixelKit {
 
     enum Parameters: Hashable {
+        public static let count = "count"
         public static let duration = "duration"
         public static let test = "test"
         public static let appVersion = "appVersion"