Add network constraints for fetching notifications with WorkManager (#6305)

* Add `isNetworkBlocked` and `isInAirGappedEnvironment` to `NetworkMonitor`.

* Improve the DI of `SyncPendingNotificationsRequestBuilder` to simplify its usage.

* Only update `isInAirGappedEnvironment` in `DefaultNetworkManager` if the current build is an enterprise one.

* Add network constraints to `DefaultSyncPendingNotificationsRequestBuilder` based on the air-gapped status.

* Add a feature flag to disable the new check, in case it doesn't work as expected.

features/networkmonitor/impl/build.gradle.kts

@@ -1,4 +1,5 @@
 import extension.setupDependencyInjection
+import extension.testCommonDependencies
 
 /*
  * Copyright (c) 2025 Element Creations Ltd.
@@ -23,4 +24,8 @@ dependencies {
     implementation(projects.libraries.core)
     implementation(projects.libraries.di)
     api(projects.features.networkmonitor.api)
+
+    testCommonDependencies(libs)
+    testImplementation(projects.libraries.matrix.test)
+    testImplementation(projects.features.networkmonitor.test)
 }