[Blockly][UI] adjust image of sensebox while compiling

[PaulaScharf]

The image should depend on the chosen sensebox model, just like the background image

[verena-witte]

• Aktuell passt auch der Text nicht zum Vorgang (Bei Nutzung von Blockly am Laptop + MCU steht beispielsweise, dass die senseBox Connect App geöffnet werden soll).
• Die Anzeige, dass der Code erfolgreich übertragen wurde, wenn bei der MCU s" die LED grün aufleuchtet, ist nicht mehr da

[BjoernLuig]

I suggest, a small white Window (for better contrast) which stays open after the download until closed. It could show

• the description of the down and upload process depend on the selected board type like @PaulaScharf and @verena-witte suggested
• additional links to information like resetting the MCU-S2 after using micropython (see https://docs.sensebox.de/docs/misc/circuitpython_esp32/)
• the better error messages done by @Thiemann96 if the download failed.

My experience with students who are often new to blockly and senseBox suggests, that blockly needs a clearer description of what is going on and expected from the user to do after the download. As I am not a real web dev i will just leave this here for now.