Adapt/retire SquareLine-based example

[aliphys]

As highlighted by @leonardocavagnis in #22:

Cannot port squarelinestudio_lvgl to v9 because SquareLine Studio is no longer compatible with LVGL. It works only with v8 and earlier.

The squarelinestudio_lvgl_v8.ino is no longer relevant and should be adapted/deleted since:

• It is not part of the examples we want our Users to interact with
• The code is not expected to compile (and is not included as part of the compile-example.yml workflow)

  Arduino_GigaDisplay/.github/workflows/compile-examples.yml

  Lines 30 to 50 in de47486

  	env:
  	UNIVERSAL_SKETCH_PATHS: |
  	- examples/backlight/SimpleBacklight
  	- examples/basic/ArduinoLogoDrawing
  	- examples/basic/SimpleText
  	- examples/camera/display_camera
  	- examples/gfx/geometrical-shapes
  	- examples/gfx/hello-world
  	- examples/gfx/touch-switch
  	- examples/imu/accelerometer
  	- examples/imu/gyroscope
  	- examples/lvgl/bar_lvgl
  	- examples/lvgl/button_lvgl
  	- examples/lvgl/check_radio_lvgl
  	- examples/lvgl/image_lvgl
  	- examples/lvgl/imu_orientation
  	- examples/lvgl/slider_lvgl
  	- examples/microphone/PDMSerialPlotter
  	- examples/rgb/SimpleRGB
  	- examples/rgb/blink

Possible solutions

Option	Positive	Negative
Remove	Quick and easy fix, reduced future maintenance. No Zendesk tickets mentioning this specific example, so should have minimal affect on Users	Library functionality scope reduced
Adapt	Retain compatibility with SquareLine Studio	Additional effort for a discontinued feature

[per1234]

I don't have any opinion regarding whether or not the example should be removed. However, it should be noted that SquareLine Studio have stated they do plan to provide LVGL 9.x support:

https://forum.squareline.io/t/q-plans-timeline-for-lvgl-9-observer-support/2782/2

LVGL9 support is planned for the upcoming April release. (And we’d like to support observers in the future.)

The library/core have backwards compatibility with LVGL 8.x, so even at this time when SquareLine Studio is only compatible with LVGL 8.x, it is still possible for users to use this example by simply installing version 8.4.0 of the "lvgl" library.

[leonardocavagnis]

I'm agree with @per1234.
Do not retire squarelinestudio_lvgl_v8.ino, we'll do the porting to LVGLv9 when the new SquareLine studio will be release.

[aliphys]

Thanks for the insight @per1234 and @leonardocavagnis . Closing this issue, and created issue #29 regarding the porting task @leonardocavagnis mentioned.