Define canonical properties for surfacing ARM metadata

[michaeltlombardi]

Summary of the new feature / enhancement

Related to #598 and #884, we need to define canonical properties for resources to use that can be surfaced in an ARM context.

Currently, we need to define:

• _name - the uniquely identifying name for an instance. According to the ARM documentation, the name must follow URI component restrictions defined in RFC3986.
• _securityContext - indicates the requisite security context for managing the instance. Must be valid for the securityContext metadata property.
• _kind - Indicates a subtype for the resource when a resource supports multiple object forms validated by different JSON subschemas. This can be an arbitrary string.

Proposed technical implementation details (optional)

We'll need to define each of these canonical properties as JSON Schemas, include them in the published schemas, and document them.