longest_query should return application_name

I'd like to see the application_name in the perfdata, something like that:

POSTGRES_LONGEST_QUERY CRITICAL: mydatabase (pg_dump): 6h26m28s

Knowing at once if this is a backup or a pgadmin4 or a batch is useful when filtering out the warnings in the morning.

Probably not as default, as it may break some graphs.

We already retrieve the application_name to exclude some queries.