[wpiutil] CircularBuffer: Change Java package-private methods to public (#4181)

The `size`, `getFirst`, `getLast`, and `resize` methods were all package-private.

Also make `size` return an `int` instead of a `double`.

wpiutil/src/main/java/edu/wpi/first/util/CircularBuffer.java

@@ -31,7 +31,7 @@ public class CircularBuffer {
    *
    * @return number of elements in buffer
    */
-  double size() {
+  public int size() {
     return m_length;
   }
 
@@ -40,7 +40,7 @@ public class CircularBuffer {
    *
    * @return value at front of buffer
    */
-  double getFirst() {
+  public double getFirst() {
     return m_data[m_front];
   }
 
@@ -49,7 +49,7 @@ public class CircularBuffer {
    *
    * @return value at back of buffer
    */
-  double getLast() {
+  public double getLast() {
     // If there are no elements in the buffer, do nothing
     if (m_length == 0) {
       return 0.0;
@@ -138,7 +138,7 @@ public class CircularBuffer {
    *
    * @param size New buffer size.
    */
-  void resize(int size) {
+  public void resize(int size) {
     double[] newBuffer = new double[size];
     m_length = Math.min(m_length, size);
     for (int i = 0; i < m_length; i++) {