WIP: Refactor JSON parser/writer, add YAML support

[ianling]

Refactors the JSON parser/writer so it no longer uses reflect. The new approach is incomparably more maintainable and less error-prone, and requires substantially fewer unit tests.

Adds YAML support.

Using Go's built-in JSON functionality gives us YAML support for free using https://pkg.go.dev/sigs.k8s.io/yaml

There are a number of breaking API changes here (I changed some of the structs to align more with the spec). Maybe once full support for all three of these file types is finished in this PR (plus RDF, which is already in the module), this warrants an API-breaking 1.0.0 release of these tools?

I'm investigating XLS support as well, which, if added, would mean that this module has full support for all of the formats listed in the spec.

[ianling]

(title of PR originally mentioned XML because I got this mixed up with CycloneDX, where XML is already a supported format)

[CatalinStratu]

Hi, @ianling, it looks great, we enjoy new contributors.

I believe that this PR should be divided into smaller PRs to make it easier to code review.

[ianling]

I am not sure how to break it into smaller chunks unfortunately; in order to maintain the same functionality in the JSON parser/writer, the entire struct refactor needs to be added at once. If I do it piecemeal, I have to go back and make changes to the old JSON parser/writer which would then be removed in my later commits.

In other words, if I break it into smaller commits, there will be commits where the tools are broken.

I can move the YAML commit into a different PR, but the changes for that are contained entirely in the yaml folder.

[CatalinStratu]

In this PR, issue #124 is fixed, but there is a new issue

[CatalinStratu]

I am not sure how to break it into smaller chunks unfortunately; in order to maintain the same functionality in the JSON parser/writer, the entire struct refactor needs to be added at once. If I do it piecemeal, I have to go back and make changes to the old JSON parser/writer which would then be removed in my later commits.

In other words, if I break it into smaller commits, there will be commits where the tools are broken.

I can move the YAML commit into a different PR, but the changes for that are contained entirely in the yaml folder.

@ianling ,yes, it is a good idea to move YAML to PR separately

[ianling]

I missed running those examples during my testing, I will do that and report back (and fix bugs I introduced). Thanks for taking a look.

[ianling]

Closing this PR in favor of #133 and #134