Catch connection error

[microbit-sam]

If the micro:bit takes 5 seconds to connect before flashing, assume somethings gone wrong and error out

• 5 seconds may be too short/long?
• What error should we use?

[microbit-carlos]

Updated the error to show pass the right error message and display the "reconnect micro:bit" text on the modal as well.
Event message becomes timeout-error/unable-to-connect-to-the-micro-bit.