[wpimath] Revert Rotation2D change that limits angles (#4781)

Reverts "[wpimath] Constrain Rotation2d range to -pi to pi (#4611)"
This reverts commit d1d458db2b.

This broke multiple teams code in beta. It is also easier to limit the angle externally, then reconstruct a larger angle that got limited. This additionally adds comments to clarify the behavior and retains tests that were added in the reverted commit, and fixes a javadoc comment angle reference.

wpilibc/src/main/native/include/frc/interfaces/Gyro.h

@@ -66,6 +66,10 @@ class Gyro {
   /**
    * Return the heading of the robot as a Rotation2d.
    *
+   * The angle is continuous, that is it will continue from 360 to 361 degrees.
+   * This allows algorithms that wouldn't want to see a discontinuity in the
+   * gyro output as it sweeps past from 360 to 0 on the second time around.
+   *
    * The angle is expected to increase as the gyro turns counterclockwise when
    * looked at from the top. It needs to follow the NWU axis convention.
    *