[Enhancement] Change some of the firmware.update behaviors via SD card

[tadeubas]

First, when Krux detects the new firmware on the SD card, it appears to have frozen because we see the Krux logo for a longer period of time than we are used to. My suggestion is to add a small firmware.bin file detected message after the code detects that there is a firmware.bin file, this would help the user know that the device is already doing something (we could also reuse the display obj , passing it as a parameter from boot.py to firmware.py to make this message appear faster)

Second, when the user cancels the installation process, Krux does not clear the text. It again appears that the device has frozen or the user input has not been captured. I suggest just cleaning the screen or writing a message like Installation cancelled. Starting Krux..

Third, when the firmware is installed successfully, the screen shows a brief message Upgrade complete. Shutting down.., sometimes the user is not looking at the device and cannot see the message, so the device restarts and the message to install the firmware is presented again, making the user think that the installation was not successful. My suggestion would be to delete the firmware.bin file to prevent the device from asking again after the automatic reboot, or inform the user that the update was successful and ask if they want to delete the firmware.bin file, before the automatic reboot (I personally prefer the first option, because if the user does not delete the file he will be forever asked about the firmware update until he removes the card from the device and deletes the file).

Fourth, it is good to show the current version of the device along with the message displayed asking if it wants to install the firmware. This way the user is aware of which version they are overwriting with the "new" firmware file.