Add a servlet Galleon Layer

This will be a new layer similar to the web-server layer without extras. It should include the following layers:

• ee-integration
• name
• undertow

It should also include the undertow-servlet feature group.

The web-server will end up depending on servlet and include an optional ee-concurrency and optional deployment-scanner dependency.

This will allow for a for the ee-core-profile to exclude concurrency from it's configuration.