Add non-compliant endpoints from Selenium

Description

Selenium currently defines these endpoints and makes them available to Appium:

  • GET_SCREEN_ORIENTATION
  • SET_SCREEN_ORIENTATION
  • GET_SCREEN_ROTATION
  • SET_SCREEN_ROTATION
  • SWITCH_TO_CONTEXT
  • GET_CURRENT_CONTEXT_HANDLE
  • GET_CONTEXT_HANDLES

We're looking at removing everything that isn't w3c compliant — SeleniumHQ/selenium#13372

So, here I am, not removing things in Selenium before making sure things are good in Appium. 😂

Thanks.