Ability to set "Run as Assignee" as the default automation executor

Problem Definition

Currently, there's only option to set project default using a username and user who trigger the rule. There's certain automation only can set the project default , for example for SLA trigger.

Suggested Solution

Option to set Assignee as the project default.

Why this is important

It's a bit weird if customer notice a different person than the assignee that perform action in the ticket.