[wpimath] Add Pose3d(Pose2d) constructor (#4485)

wpimath/src/main/native/include/frc/geometry/Pose3d.h

@@ -43,6 +43,13 @@ class WPILIB_DLLEXPORT Pose3d {
   Pose3d(units::meter_t x, units::meter_t y, units::meter_t z,
          Rotation3d rotation);
 
+  /**
+   * Constructs a 3D pose from a 2D pose in the X-Y plane.
+   *
+   * @param pose The 2D pose.
+   */
+  explicit Pose3d(const Pose2d& pose);
+
   /**
    * Transforms the pose by the given transformation and returns the new
    * transformed pose.