[main] add macros for checking specific buttons

Current implementation contains full support for:
- transparent switching between direct and framebuffer rendering modes
- writing characters to framebuffers
- loading frame from memory to physical display

As well as partial support for instruction writes including:
- resetting the display (clears memory, sets cursor at 0:0, switches to increment mode)
- switching between increment/decrement modes
- setting cursor position

Core/Src/PCA9685.c

@@ -40,8 +40,6 @@ int PCA9685_run_test(void)
 				display_write_data_seq("/5 ");
 
 				switch (op_result) {
-				case HAL_OK:
-					break;
 				case HAL_ERROR:
 					display_write_data_seq("ERROR");
 					break;