[Gijs Reijn (Gijsreyn)]

PR Summary

This change:

• Makes the linter available as dsc lint by shipping dsclint with a plug-in manifest (Microsoft.DSC/Lint).
• Carries the full content of (GH-579) Add dsclint executable #1768 on top of the command plug-ins from (GH-461) Add command plug-ins to extend dsc with new commands #1808: the lint engine in dsc-lib, the dsclint executable, the schema-error diagnostics and the lint_dsc_config MCP tool.
• Moves the lint rule settings and dsclint tracing onto the settings module that landed on main in (GH-1081) Integrate settings through CLI and lib #1769.
• Adds nine Pester tests for dsc lint, and adds dsclint to the Windows test matrix.
• Relates to Export multi methods #579 and Add ability to have plugins to dsc.exe #461.

PR Context

The earlier PR #1768 adds dsclint as a separate executable. The working group preferred to reach it as dsc lint through a plug-in system instead of a built-in subcommand. This PR shows the two together: no linter code is compiled into the dsc command, and dsc lint returns the same output and exit code as dsclint.

This branch contains the commits of #1808. Until that PR merges, the diff here includes it. Review only the merge commit and what follows.

Remarks on the design

• Port, not rewrite. The lint code is the code from (GH-579) Add dsclint executable #1768. Changes are limited to what main moved since: the settings API, the ResourceCapability rename, and resource lookup returning a trait object.
• Lint settings. lint.rules is now a field of the settings files (machine, user, workspace and policy) and is merged in that order, with policy applied last.
• Invalid lint section. It now makes that settings file fail to load with a warning, like any other invalid field. (GH-579) Add dsclint executable #1768 reported a dedicated lint settings error.
• Tracing. dsc --trace-level info lint ... applies to the linter. An option after lint overrides it.
• Version. dsclint and its manifest are at 3.4.0-preview.3 to match dsc.
• Schema errors. Resource input and output validation reports all schema errors with their location in the document, as in (GH-579) Add dsclint executable #1768.

Known gaps

• dsc help lint prints Usage: dsclint.exe.
• The lint settings field has no schema documentation strings yet.
• The manifest is in the build's file lists, but the MSIX, RPM and DEB packaging isn't verified.