Origin/user/benhillis/launcher v2

[benhillis]

This change is primarily a simplification to the existing distribution launcher sample to prepare for open sourcing. It contains three major pieces of work:

1. Minimize size of code (roughly 700 lines less than previous version).
2. Arm64 architecture support (still some work needed).
3. Bugfixes (not a complete list):
   • Plumb process exit code from launched Linux binary
   • Improve error logging with user-readable messages
   • Simplify user creation.