Implement default values for references

[simu]

We treat :: as the delimiter between reference path and default value. Note that this is technically a breaking change for existing reclass-rs inventories.

The implementation currently first resolves all nested references in both the reference and the default value parts before even looking for : and ::.

We always parse the default value as YAML to support complex default values (directly or via reference) and to provide the most intuitive default value behavior (any valid YAML snippets are used as typed values, and malformed snippets raise errors).

To make usage of simple default values more intuitive, we convert parsed string default value into Value::Literal to avoid incorrect additional reference resolution. We know that we've already resolved the top-level nested references at the time we parse a default value.

Note that we don't want to recursively replace Value::String with Value::Literal so that default values which are references that expand to complex values still get resolved correctly.

Generally, we recommend that users use references when they want to provide complex default values, since complex default values which are provided inline require special care to not confuse the reference and default parsers.

Checklist

• The PR has a meaningful title. The title will be used to auto generate the changelog
• PR contains a single logical change (to build a better changelog).
• Update the documentation.
• Update tests.
• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency, internal
  as they show up in the changelog

[github-actions]

Benchmark for 7a2368a

Click to view benchmark

Test	Base	PR	%
Reclass::inventory() multi-threaded	2.3±0.12ms	2.3±0.14ms	0.00%
Reclass::inventory() single-threaded	4.6±0.09ms	4.6±0.06ms	0.00%

[simu]

If you have a bit of time when reviewing please think about potentially missing test cases.

[bastjan]

🥳

Did not find any additionally required test cases from the top of my head.