Calibrate ruler on the ruler page

[kylecorry31]

This would make use of the tap to measure feature.

It would ask the user to measure 1 inch/cm on the real ruler and tap where that lines up on Trail Sense. It should update the ruler display in real time to provide feedback and have a button to save or cancel (replaces main content on the ruler). The user should also be able to reset the calibration on the same screen.