[fenix] For https://github.com/mozilla-mobile/fenix/issues/11051 - added intent check for voice search

Also made the activity translucent so that it won't flicker when the user pressses the button and Google app is disabled

app/src/main/AndroidManifest.xml

@@ -215,7 +215,8 @@
             android:name=".crashes.CrashListActivity"
             android:exported="false" />
 
-        <activity android:name=".widget.VoiceSearchActivity" />
+        <activity android:name=".widget.VoiceSearchActivity"
+            android:theme="@style/Theme.AppCompat.Translucent"/>
 
         <activity
             android:name=".settings.account.AuthCustomTabActivity"

app/src/main/java/org/mozilla/fenix/widget/VoiceSearchActivity.kt

@@ -34,6 +34,11 @@ class VoiceSearchActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
+        if (Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH).resolveActivity(packageManager) == null) {
+            finish()
+            return
+        }
+
         // Retrieve the previous intent from the saved state
         previousIntent = savedInstanceState?.get(PREVIOUS_INTENT) as Intent?
         if (previousIntent.isForSpeechProcessing()) {