external plugin client: use verificationexception for security exceptions

runelite-client/src/main/java/net/runelite/client/externalplugins/ExternalPluginClient.java

@@ -111,7 +111,7 @@ public class ExternalPluginClient
 		}
 		catch (NoSuchAlgorithmException | InvalidKeyException | SignatureException e)
 		{
-			throw new RuntimeException(e);
+			throw new VerificationException(e);
 		}
 	}
 

runelite-client/src/main/java/net/runelite/client/util/VerificationException.java

@@ -31,6 +31,11 @@ public class VerificationException extends Exception
 		super(message);
 	}
 
+	public VerificationException(Throwable cause)
+	{
+		super(cause);
+	}
+
 	public VerificationException(String message, Throwable cause)
 	{
 		super(message, cause);