Set up async runtime

This adds tokio to the project and wraps the main function with an async
executor.

Change-Id: Iff66164dfe374e7ff1ab929f99e5674e464a730f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/qg/+/119751
Reviewed-by: Erik Gilling <konkers@google.com>
Commit-Queue: Alexei Frolov <frolv@google.com>
3 files changed
tree: c6379afe09a2f88597967261ba7d27666cc9448c
  1. qg/
  2. qg-cli/
  3. tools/
  4. .gitignore
  5. Cargo.lock
  6. Cargo.toml
  7. rustfmt.toml