Saved search folders should be visible in the messaging menu

[Roquentin]

When emails matching a saved search arrive, the corresponding folders are not included in the messaging menu. Actual folders are included, but saved search folders should be included too.

Use case to illustrate this problem: Mike has created a saved search folder called Critical matching emails from collaborators in some important projects. These are typically messages that need his attention and should be read right away. When the envelope tunrns blue he clicks on the icon and checks if the Critical folder is present. If not he can continue to focus on his work.

Without this feature Mike should open the TB window every time to check.