CPS In-Memory profile support

[Irame]

Introduce an option/setting to enable CPS In-Memory profile support.

In memory profiles are a feature to create a launch profile in CPS projects without writing it into the launch.json.

When this option is set a virtual launch profile is created and maintained. Changes to the parameters are only applied to this launch profile or when this launch profile is enabled.

This feature was initially proposed by mitchcapper in PR #147 and later #151. I am sorry I left it for so long.
There is a stale branch cps_inmemory_profile for this, but due to the project restructuring I am creating a new one.
Also see dotnet/project-system#7010 where he contributed to the conservation around a (semi-)stable version of Microsoft.VisualStudio.ProjectSystem.Managed.