Notify users for invalid client settings

[dhruvmanila]

Summary

As mentioned in #16296 (comment)

This PR updates the client settings resolver to notify the user if there are any errors in the config using a very basic approach. In addition, each error related to specific settings are logged.

This isn't the best approach because it can log the same message multiple times when both workspace and global settings are provided and they both are the same. This is the case for a single workspace VS Code instance.

I do have some ideas on how to improve this and will explore them during my free time (low priority):

• Avoid resolving the global settings multiple times as they're static
• Include the source of the setting (workspace or global?)
• Maybe use a struct (ResolvedClientSettings + Vec<ClientSettingsResolverError>) instead to make unit testing easier

Test Plan

Using:

{
  "ruff.logLevel": "debug",
	
  // Invalid settings
  "ruff.configuration": "$RANDOM",
  "ruff.lint.select": ["RUF000", "I001"],
  "ruff.lint.extendSelect": ["B001", "B002"],
  "ruff.lint.ignore": ["I999", "F401"]
}

The error logs:

2025-02-27 12:30:04.318736000 ERROR Failed to load settings from `configuration`: error looking key 'RANDOM' up: environment variable not found
2025-02-27 12:30:04.319196000 ERROR Failed to load settings from `configuration`: error looking key 'RANDOM' up: environment variable not found
2025-02-27 12:30:04.320549000 ERROR Unknown rule selectors found in `lint.select`: ["RUF000"]
2025-02-27 12:30:04.320669000 ERROR Unknown rule selectors found in `lint.extendSelect`: ["B001"]
2025-02-27 12:30:04.320764000 ERROR Unknown rule selectors found in `lint.ignore`: ["I999"]

Notification preview:

[github-actions]

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