… when local changes are detected

The initial idea was to display such a warning only
when changes are detected in the Devfile,
which are not yet handled completely at this time.
But to take into account the manual synchronization case (where
there is no file watcher (and therefore no way to determine which
files have actually been modified)), a generic warning is being
displayed whenever the Podman-specific watch handler is called.

…started when local changes are detected

Display a warning that "odo dev" on Podman might need to be restarted when the Devfile is modified