Chat Sessions: Add Mark All Read action

[chrmarti]

Not sure if this is specific to us testing sessions, but I at some point wished I could just mark all sessions as "read".

[bpasero]

We have an action per section:

But I think we could have actions to mark all as read / archive all from a session too.

[bpasero]

We already have a command to archive all agent sessions in the workspace, I am adding a command to support the same for marking as read.

[chrmarti]

I don't have the "Today" section. Now that I know I see the mark all read action in the context menu of the More section. I guess context menus on sections might be difficult to discover.