LVGL Support for 3 buttons as rotary encoder

[s-hadinger]

Description:

Added support for 3 physical buttons that act as a rotary encoder: LEFT-PRESS-RIGHT. The buttons must be declared as INPUT <n> in the Tasmota template.

Working example with M5Stack Core:

g = lv_group()
g.add_obj(prev_btn)
g.add_obj(home_btn)
g.add_obj(next_btn)
rotary = lv.add_button_encoder(true)	#- buttons are inverted -#
rotary.set_group(g)

Internally:

• Added new lv_indev class for input devices
• Added support for rotary type buttons
• More will follow

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works on Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with core ESP32 V.1.0.6
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass