Update to LVGL 9.0.0 (#47)

- Updated LVGL from 8.3 to 9.0 (removed example/docs/demo folders)
- Updated esp_lvgl_port  to current status of the `lvgl9` branch on `esp-bsp`: https://github.com/espressif/esp-bsp/tree/lvgl9
- Updated all boards and drivers
- Removed `libs/lv_drivers` subproject as SDL is now supported by LVGL directly (although keyboard input seems broken)
- Updated `libs/lv_screenshot`
- Fixed the way `tt_statusbar` widget works due to behaviour change in LVGL
- Updated other lvgl code

libs/lvgl/scripts/release/release.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-# Create a new release from master. Execute the followings:
+# Create a new release from master. Execute the following:
 # - On lvgl, lv_demos, and lv_drivers:
 #   - Detect the current version of master. E.g. 8.1-dev
 #   - Create a new branch from the master for the release. E.g. release/v8.1