For #2893, #2673, #2916, #2314: Fix race condition navigating to browser (#3023)

Since the Navigation library restores the fragment after memory eviction, if we're already on the BrowserFragment and we deep link navigate to the BrowserFragment, we briefly get two of them. This crashes GeckoView.

CHANGELOG.md

@@ -64,4 +64,5 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - #654 - Updated Refresh button to turn into Stop button while menu is open.
 - [AC #2725](https://github.com/mozilla-mobile/android-components/issues/2725) Updated tracking protectionPolicy to [recommend](https://github.com/mozilla-mobile/android-components/blob/master/components/concept/engine/src/main/java/mozilla/components/concept/engine/EngineSession.kt#L156)
 - #2789 Custom tabs is not covering the full screen size.
+- #2893, #2673, #2916, #2314: Fix several crashes navigating from external links
 ### Removed

app/src/main/java/org/mozilla/fenix/HomeActivity.kt

@@ -156,7 +156,8 @@ open class HomeActivity : AppCompatActivity() {
     }
 
     private fun handleOpenedFromExternalSourceIfNecessary(intent: Intent?) {
-        if (intent?.extras?.getBoolean(OPEN_TO_BROWSER) != true) { return }
+        if (navHost.navController.currentDestination?.id == R.id.browserFragment) return
+        if (intent?.extras?.getBoolean(OPEN_TO_BROWSER) != true) return
 
         this.intent.putExtra(OPEN_TO_BROWSER, false)
         var customTabSessionId: String? = null