[pkg_resolver] Rewrite rules toggle amber sources

This reverts commit b3099baf2e433f3c1450a07ac232e27a97ab3ed0, which was
a revert of commit e78ed1e2062564d3cf29d63ee5edf07f8dc5ba97, which was
essentially this commit.

When pkg_resolver's rewrite rules change, it will now make a best effort
to exclusively enable all matching amber sources with an equivalent ID,
if there is a rewrite rule that rewrites all of fuchsia.com.

Additionally, amberctl now enables and disables amber sources by
managing rewrite rules. A side effect of this change is that it can no
longer reasonably support enabling multiple sources, so it now ignores
the "-x" flag if provided, always ensuring there is 0 or 1 enabled Amber
source.

Test: CQ
PKG-799 #done

Change-Id: I47a18647624101b9054c95c6f9bd9f36e0d4a278
11 files changed
tree: 85cb21b02d129f78ee4ac64d17810242433610dc
  1. boards/
  2. build/
  3. buildtools/
  4. bundles/
  5. docs/
  6. examples/
  7. garnet/
  8. peridot/
  9. products/
  10. scripts/
  11. sdk/
  12. src/
  13. third_party/
  14. tools/
  15. zircon/
  16. .clang-format
  17. .clang-tidy
  18. .dir-locals.el
  19. .gitattributes
  20. .gitignore
  21. .gn
  22. AUTHORS
  23. BUILD.gn
  24. CODE_OF_CONDUCT.md
  25. CONTRIBUTING.md
  26. LICENSE
  27. OWNERS
  28. PATENTS
  29. README.md
  30. rustfmt.toml
README.md

Fuchsia

Pink + Purple == Fuchsia (a new operating system)

What is Fuchsia?

Fuchsia is a modular, capability-based operating system. Fuchsia runs on modern 64-bit Intel and ARM processors.

Fuchsia is an open source project with a code of conduct that we expect everyone who interacts with the project to respect.

How can I build and run Fuchsia?

See Getting Started.

Where can I learn more about Fuchsia?

See the documentation.