[wpiunits] Add InchesPerSecondPerSecond (#7905)

Author: WispySparks

wpiunits/src/main/java/edu/wpi/first/units/Units.java

@@ -203,6 +203,12 @@ private Units() {
    */
   public static final LinearAccelerationUnit FeetPerSecondPerSecond = FeetPerSecond.per(Second);
 
+  /**
+   * A unit of linear acceleration equivalent to accelerating at a rate of one {@link #Inch Inch}
+   * per {@link #Second} every second.
+   */
+  public static final LinearAccelerationUnit InchesPerSecondPerSecond = InchesPerSecond.per(Second);
+
   /**
    * A unit of angular acceleration equivalent to accelerating at a rate of one {@link #Rotations
    * Rotation} per {@link #Second} every second.