Replace usages of `nanoFramework.UI.Point` with `System.Drawing.Point`

[CoryCharlton]

Description

Replace usages of nanoFramework.UI.Point with System.Drawing.Point once nanoframework/nanoFramework.Graphics#133 is merged.

How to solve the problem

CTRL+SHIFT+F, replace in files...

Describe alternatives you've considered

No response

Aditional context

No response

[josesimoes]

Hey @CoryCharlton guess it's OK to move forward with this, correct? 😉

[CoryCharlton]

I checked and the only usage I could find was already updated (by the bot?): nanoframework/nanoFramework.IoT.Device@0c19511