Fix when resource test returns '_inDesiredState', that takes precedence

[SteveL-MSFT]

PR Summary

Even when a resource implement test returns state and contains _inDesiredState property, that value isn't being used and a synthetic comparison still occurs.

With this change, whether a resource returns state or stateAndDiff and contains _inDesiredState, then that value will be used regardless if there are any differing properties. Diff of properties will still occur for information purposes even if _inDesiredState = true

Also fixed a resource string issue where the placeholder wasn't being replaced correctly.

PR Context

Fix #674

[Copilot]

PR Overview

This PR fixes the issue where a resource’s _inDesiredState property is ignored in the test process and addresses a resource string placeholder replacement.

• Introduces a new InDesiredState struct in dsctest to clearly encapsulate the in‐desired‐state information.
• Adjusts command_resource.rs to prioritize the _inDesiredState value over synthetic diff comparison.
• Adds a new subcommand and CLI support for the in-desired-state test along with a corresponding JSON schema and localized message updates.

Reviewed Changes

File	Description
tools/dsctest/src/in_desired_state.rs	Added InDesiredState struct to hold resource state and a supporting field.
dsc_lib/src/dscresources/command_resource.rs	Updated invoke_test to consider _inDesiredState for determining desired state.
tools/dsctest/src/main.rs	Introduced InDesiredState subcommand and handling of its JSON input.
tools/dsctest/src/args.rs	Extended CLI argument parsing for the new in-desired-state subcommand.
dsc_lib/locales/en-us.toml	Fixed string placeholder for the executable in error messages.

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

tools/dsctest/src/in_desired_state.rs:12

• [nitpick] The field name 'value' is ambiguous; consider renaming it to better reflect its purpose, such as 'state_description' or another descriptive term.

pub value: String,

[SteveL-MSFT]

Was thinking about this and originally I figured that if a resource returned stateAndDiff that the diff would determine if in desired state, but I think we should just trust the resource regardless if there is a diff or not. So I'll make that change.

[SteveL-MSFT]

@tgauth please continue the review