Add a new Azure.Core helper that returns version and projection Info

[markcowl]

Create a new helper that returns appropriate version projections info for a service

interface ServiceVersion {
  version: string,
  getProjectedProgram(program: Program): ProjectedProgram;
}

export function buildServiceVersionProjections( program: Program, service: Service): ServiceVersion[];

This function should ensure that the `version

[markcowl]

• defer until after DPG discussion 1/18

[markcowl]

No longer needed, as service.version is being deprecated