[realm_builder] Format ErrorList messages

This CL makes the format for cm_fild_analyzer::error::ErrorList
structured, helping it be more readable for users. It turns:

```
[98805.927319][18733956][18733958][realm_builder_server] WARN: unable to replace realm decl: a component manifest failed validation: ErrorList { errs: [InvalidField(DeclField { decl: "ExposeProtocol", field: "source_name" }), InvalidField(DeclField { decl: "ExposeProtocol", field: "target_name" })] }
```

To:

```
[00060.285693][50201][50203][realm_builder_server] WARN: The constructed component declaration is invalid. Please fix all the listed errors:
  1. "secho_server" is referenced in ExposeProtocol.source but it does not appear in children. Declare one in the `children` section of the component declaration with the name "secho_server" in order to reference it.
  2. Field `target` for ExposeProtocol is invalid.
  3. Field `source_name` is missing for ExposeProtocol decl. Add this field to the component declaration.
For a reference as to how component declarations are authored, see https://fuchsia.dev/go/components/declaration. method=Realm.ReplaceRealmDecl
```

Fixed: 100731
Change-Id: I4b8659ca66586fa32bcd34f5a1eeadcdeac16dd6
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/689505
Commit-Queue: Yaneury Fermin <yaneury@google.com>
Reviewed-by: Gary Bressler <geb@google.com>
4 files changed
tree: 006db217e495ebe689545799958a18ad0c93ead3
  1. boards/
  2. build/
  3. bundles/
  4. docs/
  5. examples/
  6. products/
  7. scripts/
  8. sdk/
  9. src/
  10. third_party/
  11. tools/
  12. zircon/
  13. .clang-format
  14. .clang-tidy
  15. .editorconfig
  16. .git-blame-ignore-revs
  17. .gitattributes
  18. .gitignore
  19. .gn
  20. .style.yapf
  21. analysis_options.yaml
  22. AUTHORS
  23. BUILD.gn
  24. CODE_OF_CONDUCT.md
  25. CONTRIBUTING.md
  26. LICENSE
  27. OWNERS
  28. PATENTS
  29. pyrightconfig.json
  30. README.md
  31. rustfmt.toml
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.