Add curtains

[JELoohuis]

• Added support for curtain devices
  Added support for 'cl' Tuya devices.
  The following capabilities were implemented:

  • control (windowcoverings_state)
  • mach_operate (windowcoverings_state)
  • position (windowcoverings_set)
  • percent_control (windowcoverings_set)
  • percent_state (windowcoverings_set)

  The following capabilities were implemented as settings:

  • opposite (inverse)
  • control_back (inverse)
  • control_back_mode (inverse)

  No device was available to test these capabilities

[bobvandevijver]

Haven't checked the code, but you only implemented the position code, which is legacy. All requested devices use percent_control.