Expose MSP bitmask on wire via common properties API

[maxgolov]

This ask comes from Office Desktop telemetry.

The new MSP flags / bitmask field allows to determine what ring / group the user belongs to; also allows to enable routing of a subset of data to Enterprise Data Platform.

Requirements:

• allow the customer to set MSP flags via API call at individual event-level (SetProperty or SetContext)
• send MSP flag on wire in Bond 3.0+ schema to Collector++

[maxgolov]

Further clarity needed from OTEL team if they believe this item is required.
On-hold - pending review.

[maxgolov]

Retarget to August.

[maxgolov]

Retarget to September, as we had no feedback from OTEL if this is still required.

[maxgolov]

#118 will add a way for the app to populate the MSP bitmask. SDK does not know how to fetch nor what registry keys to use for that. It is the app that should identify the target audience, set the bits and use a custom decorator on matching events to route these to EDP using MSP bits. Sample app with a custom decorator will be provided.

[maxgolov]

No timeline. Logged documentation issue against CS4.0:
https://github.com/microsoft/common-schema/issues/21

[maxgolov]

Based on feedback from Office teams - this is not a priority at least until the end of April 2020.

[maxgolov]

MSP bit added in Common Schema 4.0 CsEvent in #118 . It can be populated using Custom Decorator, which was also added in this PR. I'm closing this issue until some team explicitly asks for MSP support, other than based on Custom Decorator approach.