LVGL add 'lv.set_paint_cb()' to register a callback when screen is refreshed

[s-hadinger]

Description:

LVGL/Berry add an ability to set a Berry callback when the screen is refreshed.

Example:

def paint(x1,y1,x2,y2,pixels)
  import introspect
  pixels = introspect.toptr(pixels)
  log(f">>>: paint {x1=} {y1=} {x2=} {y2=} {pixels=}", 2)
end

import cb
var paint_cb = cb.gen_cb(paint)
lv.set_paint_cb(paint_cb)

lv.scr_act().invalidate()

Example of output:

12:40:45.366 >>>: paint x1=0 y1=0 x2=171 y2=79 pixels=<ptr: 0x4082ea10>
12:40:45.376 >>>: paint x1=0 y1=80 x2=171 y2=159 pixels=<ptr: 0x4082ea10>
12:40:45.388 >>>: paint x1=0 y1=160 x2=171 y2=239 pixels=<ptr: 0x4082ea10>
12:40:45.398 >>>: paint x1=0 y1=240 x2=171 y2=319 pixels=<ptr: 0x4082ea10>

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 with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.1.1.250109
• I accept the CLA.

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