tls: Check RSA presence in .pem certificate

Disable Private Key File choise if RSA key is in .pem

Refs #45008
diff --git a/src/org/sflphone/fragments/NestedSettingsFragment.java b/src/org/sflphone/fragments/NestedSettingsFragment.java
index ead7cda..6dab587 100644
--- a/src/org/sflphone/fragments/NestedSettingsFragment.java
+++ b/src/org/sflphone/fragments/NestedSettingsFragment.java
@@ -97,6 +97,15 @@
         return false;
     }
 
+    public boolean findRSAKey(String pemPath) {
+        try {
+            return mCallbacks.getService().checkForPrivateKey(pemPath);
+        } catch (RemoteException e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+
     public interface Callbacks {
 
         public Account getAccount();