[wpilib] Add AnalogEncoder(int) ctor (#3273)

wpilibj/src/main/java/edu/wpi/first/wpilibj/AnalogEncoder.java

@@ -23,6 +23,15 @@ public class AnalogEncoder implements Sendable, AutoCloseable {
   protected SimDevice m_simDevice;
   protected SimDouble m_simPosition;
 
+  /**
+   * Construct a new AnalogEncoder attached to a specific AnalogIn channel.
+   *
+   * @param channel the analog input channel to attach to
+   */
+  public AnalogEncoder(int channel) {
+    this(new AnalogInput(channel));
+  }
+
   /**
    * Construct a new AnalogEncoder attached to a specific AnalogInput.
    *