ESPHome dashboard should offer two update buttons - "Update" and "Update all"

The current "Update" button in the ESPHome dashboard is only of limited use. It triggers an update of all devices independent of whether individual devices are already running the latest ESPHome firmware.

This not only prolongs the update process unnecessarily (up-to-date devices are not skipped) but is also super annoying if, on the way, one particular update doesn't work/fails. In this case the whole update process starts from the very beginning again and not only from the faulty devices. Super annoying.

I propose to have two buttons:
"Update all": as the name suggests, this updates all devices independent of their firmware version
"Update": only updates devices for which there is a newer version of the firmware available / that haven't been updated yet.

Start by locating the ESPHome dashboard's current update control and the flow it triggers for device updates. Define how the two actions distinguish all devices from only devices with newer or missing firmware, then verify that already-current devices are skipped and failures do not restart completed updates.

Written by the indexing model from the issue text.