Add a prop to add active Item in conversation list

[karthikjeeyar]

Add a prop to add active Item in conversation list. RHDH is saving the conversation history and while the user logs in back, we are trying to show the last opened conversation and we need that conversation to be active/selected.

[rebeccaalpert]

I'm putting up a quick PR to allow passage of menuItem props onto the menuItem, but let me just check with design tomorrow to make sure this sort of thing is ok.

Let me know if you're looking for something else here.

[karthikjeeyar]

When you hover or click on the menu Item, there is a darker background color that gets applied and highlights the selection. I was thinking if we could do the same for the activeItem as well. wdyt?

[rebeccaalpert]

I'll pass your comment along and ask design! :)

[kaylachumley]

Let's apply an active/clicked state to the current nav item using pf-t--global--background--color--action--plain--clicked