Reland "[ffx][emu] Find an unused CID to use"

This is a reland of commit 45cecafb7009c23ba5a88a2438b3814f68fdc30a

Original change's description:
> [ffx][emu] Find an unused CID to use
>
> Rather than just rely on the CID provided in the virtual device, we
> instead find one dynamically at runtime.
>
> Change-Id: I0201b7c06d2d4cdfaa651b2affe725573f0e7f4d
> Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1207226
> Fuchsia-Auto-Submit: Suraj Malhotra <surajmalhotra@google.com>
> Reviewed-by: Casey Dahlin <sadmac@google.com>
> Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>

Change-Id: I6387731a44ddd455fca32dcdb279731cf4294340
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1209093
Reviewed-by: Casey Dahlin <sadmac@google.com>
Mega-CQ: Suraj Malhotra <surajmalhotra@google.com>
Commit-Queue: Suraj Malhotra <surajmalhotra@google.com>
3 files changed
tree: 84b4bf5c55e762091c298e5037fe8b1aa7e64aa7
  1. .helix/
  2. boards/
  3. build/
  4. bundles/
  5. docs/
  6. examples/
  7. infra/
  8. products/
  9. scripts/
  10. sdk/
  11. src/
  12. third_party/
  13. tools/
  14. zircon/
  15. .clang-format
  16. .clang-tidy
  17. .editorconfig
  18. .git-blame-ignore-revs
  19. .gitattributes
  20. .gitignore
  21. .gitmodules
  22. .gn
  23. .ignore
  24. analysis_options.yaml
  25. AUTHORS
  26. BUILD.gn
  27. CODE_OF_CONDUCT.md
  28. CONTRIBUTING.md
  29. fuchsia.code-workspace
  30. LICENSE
  31. OWNERS
  32. PATENTS
  33. pyproject.toml
  34. pyrightconfig.json
  35. README.md
  36. rustfmt.toml
  37. shac.star
  38. shac.textproto
README.md

Fuchsia

What is Fuchsia?

Fuchsia is an open source, general purpose operating system supporting modern 64-bit Intel and ARM processors.

We expect everyone interacting with our project to respect our code of conduct.

Read more about Fuchsia's principles.

How can I build and run Fuchsia?

See Getting Started.

Where can I learn more about Fuchsia?

See fuchsia.dev.