allow variables to be used in alert templates recipient

[P6g9YHK6]

Is your feature request related to a problem? Please describe.
Currently only manual work is possible when sending email alerts to different recipients and when recipients can be as many a 1 per devices/site the number of alert template can quickly get out of control

Describe the solution you'd like
allow to use all the possible variables Global/client/site/agent as a recipient for an email alert template.

Describe alternatives you've considered
a butload of different template

Additional context