Added Ones and Twos Complement

Author: Monk-AbhinayVerma

src/main/java/com/thealgorithms/bitmanipulation/OnesComplement.java

@@ -8,7 +8,7 @@
  *            the complemented binary string.
  * @return the complimented binary string
  */
-public class OnesComplement {
+public final class OnesComplement {
     private OnesComplement() {
     }
 

src/main/java/com/thealgorithms/bitmanipulation/TwosComplement.java

@@ -6,7 +6,7 @@
  * @author - https://github.com/Monk-AbhinayVerma
  * @return the two's complement of any binary number
  */
-public class TwosComplement {
+public final class TwosComplement {
     private TwosComplement() {
     }