Remove `Microsoft.DSC` metadata namespace

[SteveL-MSFT]

Summary of the new feature / enhancement

There are currently two categories of content in Microsoft.DSC:

Directive:

• executionType
• requireAdapter
• resourceDiscovery
• securityContext

ExecutionInformation:

• duration
• startDatetime
• endDatetime
• operation
• restartRequired
• version

Proposed technical implementation details (optional)

In 3.2, we add a warning message to any content put under Microsoft.DSC namespace
In 3.2, we add directive and executionInformation as new config and resource level optional properties. directive are things the engine would use and executionInformation is read-only that is returned by the engine after deployment. Any values under executionInformation in the config would be an error.