For #17804: Use enterToImmersiveMode from support-ktx component

app/src/main/java/org/mozilla/fenix/browser/BaseBrowserFragment.kt

@@ -110,7 +110,6 @@ import org.mozilla.fenix.downloads.DynamicDownloadDialog
 import org.mozilla.fenix.ext.accessibilityManager
 import org.mozilla.fenix.ext.breadcrumb
 import org.mozilla.fenix.ext.components
-import org.mozilla.fenix.ext.enterToImmersiveMode
 import org.mozilla.fenix.ext.getPreferenceKey
 import org.mozilla.fenix.ext.hideToolbar
 import org.mozilla.fenix.ext.metrics
@@ -129,6 +128,7 @@ import java.lang.ref.WeakReference
 import mozilla.components.feature.session.behavior.EngineViewBrowserToolbarBehavior
 import mozilla.components.feature.webauthn.WebAuthnFeature
 import mozilla.components.support.base.feature.ActivityResultHandler
+import mozilla.components.support.ktx.android.view.enterToImmersiveMode
 import mozilla.components.feature.session.behavior.ToolbarPosition as MozacToolbarPosition
 
 /**

app/src/main/java/org/mozilla/fenix/ext/Activity.kt

@@ -15,6 +15,13 @@ import mozilla.components.concept.base.crash.Breadcrumb
  * We don't use the equivalent function from Android Components because the stable flag messes
  * with the toolbar. See #1998 and #3272.
  */
+@Deprecated(
+    message = "Use the Android Component implementation instead.",
+    replaceWith = ReplaceWith(
+        "enterToImmersiveMode()",
+        "mozilla.components.support.ktx.android.view.enterToImmersiveMode"
+    )
+)
 fun Activity.enterToImmersiveMode() {
     window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
     // This will be addressed on https://github.com/mozilla-mobile/fenix/issues/17804