MySQL User Details Dashboard: View selected user's queries in Query Analytics Dashboard

Use case: 

As  A PMM Use*r, I need to be able *to drill down from Mysql User Details dashboard to QAN with specific Service and User  so that I can see the queries created by the selected user 

User interaction:

• go to  Mysql user Details dashboard 
• Click on  any user in Total Session panel 
• go to QAN with appropriate filters 

Technical details:

It's required to add an additional variable username to the list of already added variables on all dashboards. Such variables allow to store selected filters during surfing between dashboards and QAN.