cubicweb #2547026 statement timeout to limit denial of service [in-progress]

use https://www.logilab.org/115266 to add a configuration option to CW, in order to have it automatically configure sessions timeouts depending on the user connected.

It could look like this in the configuration file:

anynomous-sql-session-timeout=30s
authenticated-sql-session-timeout=1min
admin-sql-session-timeout=0
priorityimportant
typeenhancement
appeared in<not specified>
done in3.20.0
closed by<not specified>
patchAdd a db-statement-timeout option for postgresql sources [reviewed]