Manage mail.smtp.timeout using SysConfig

Added the documentation at

and pull request 2465

Reopening because the configuration is incomplete, there are other two timeout configuration for SMTP that are worthy to implement too:
https://javaee.github.io/javamail/docs/api/index.html?com/sun/mail/smtp/package-summary.html
mail.smtp.connectiontimeout
mail.smtp.writetimeout

Our problem was on a server that cat read but not write, because the mail.smtp.timeout is just for reading it pass the test but then it takes too long there to raise an error because it cannot write.

Hi
The wiki page was already updated, but the link here was missing

Please add the documentation at https://wiki.idempiere.org/en/System_Configurator_(Window_ID-50006)