Implement RAR-out-of-proc basic execution

[ccastanedaucf]

Context

Implements the minimum serialization types and plumbing to fully execute RAR on the out-of-proc node.

Changes

• Implement task parameter parsing and serialization for RarNodeExecuteRequest and RarNodeExecuteResponse
• Replace stubs in OutOfProcRarClient and OutOfProcRarNodeEndpoing which enable full execution
• Add basic end-to-end tests for full out-of-proc execution path

Notes

To keep the size of the PR a bit reasonable, other packet types are left as stubs (client-specific setup, log message replay). E.g. RAR will actually execute more work than the client here due to immutable directories not being passed for those based on evaluated properties (nuget cache, dotnet install dirs).