Core2 M5Unified independence + general fixes (#142)

- Change init sequence: I2C is now initialized before "power" init phase, to allow for I2C power control
- I2c HAL: Added read/write support for registers
- Added axp192 code from https://github.com/tuupola/axp192 to Core2 implementation
- Fixes for Core2Power
- Fix for root project CMakeLists.txt

CMakeLists.txt

@@ -49,9 +49,6 @@ if (DEFINED ENV{ESP_IDF_VERSION})
         set(EXCLUDE_COMPONENTS "M5stackCoreS3")
     endif()
 
-    # TEMP - DO NOT COMMIT
-    set(EXCLUDE_COMPONENTS "YellowBoard" "M5stackCore2" "WaveshareS3Touch")
-
     # LVGL
     get_filename_component(
         LVGL_CONFIG_FULL_PATH Libraries/lvgl_conf ABSOLUTE