If nested calls to RunUnsynced are running, then using a bool would cause the flag to be reset once the inner function completes, but an outer function may still be running and not yet ready for the flag to be reset. To correctly handle nested calls, we track a count and only reset the flag once all functions have completed.
As the solution currently targets .NET 6, a variety of style rules only introduced in .NET 7 are not suitable for enforcing as warnings (which are treated as errors in the CI pipeline). Anybody compiling locally with a .NET 6 SDK won't be able to trigger these rules locally, but the Linux CI agent comes with the .NET 7 SDK and will trigger these rules. This provides a poor dev experience as the CI run will report errors that don't reproduce locally.
To remove this developer friction, reduce the severity of these rules to avoid CI runs failing.
This changeset is motivated by a simple concept - get rid of the MiniYaml.Clone and MiniYamlNode.Clone methods to avoid deep copying yaml trees during merging. MiniYaml becoming immutable allows the merge function to reuse existing yaml trees rather than cloning them, saving on memory and improving merge performance. On initial loading the YAML for all maps is processed, so this provides a small reduction in initial loading time.
The rest of the changeset is dealing with the change in the exposed API surface. Some With* helper methods are introduced to allow creating new YAML from existing YAML. Areas of code that generated small amounts of YAML are able to transition directly to the immutable model without too much ceremony. Some use cases are far less ergonomic even with these helper methods and so a MiniYamlBuilder is introduced to retain mutable creation functionality. This allows those areas to continue to use the old mutable structures. The main users are the update rules and linting capabilities.
