Backport: Fix discovering incompatible resource manifests to be non-fatal

[SteveL-MSFT]

PR Summary

When having both 3.1 and 3.2-preview installed, 3.1 fails because during discovery it finds the 3.2 resources which have an updated manifest that 3.1 doesn't deserialize. This ends up stopping the entire discovery process making 3.1 unusable.

This change handles the case whether an extension or DSC itself finds an incompatible resource manifest and emits an info message and skips that resource. This means that any future changes to the schema won't break the existing version.

[Copilot]

Pull request overview

Addresses a discovery failure mode where encountering an incompatible/invalid resource manifest (e.g., from a newer DSC/extension version) aborts discovery, making older versions unusable when both are installed.

Changes:

• Make extension-driven discovery skip manifests that fail to load, logging an info message instead of failing discovery.
• Make command-based discovery log invalid manifest load failures as info (localized) and continue.
• Add PowerShell tests asserting invalid manifests are skipped and produce INFO log entries.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
dsc_lib/src/extensions/dscextension.rs	Swallows load_manifest failures during extension discovery and logs at info while continuing.
dsc_lib/src/dscerror.rs	Removes an unused tracing::error import.
dsc_lib/src/discovery/command_discovery.rs	Changes invalid manifest logging from warn! to localized info! and continues discovery.
dsc_lib/locales/en-us.toml	Adds new localized strings for “failed to load manifest” scenarios.
dsc/tests/dsc_extension_discover.tests.ps1	Adds coverage ensuring invalid manifests returned by an extension don’t break overall discovery.
dsc/tests/dsc_discovery.tests.ps1	Adds coverage ensuring invalid resource manifests produce an INFO message and don’t fail listing.
build.ps1	Updates clippy “unclean” project path entries.

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