1. Renamed "Set Rule Set Severity" command to "Set severity". Also renamed "Info" and "Hidden" sub-menus to "Suggestion" and "Silent" respectively to align with our editorconfig severity terminology.
2. The set severity command handler checks if the project uses no ruleset or the default built-in ruleset, and if so it adds or updates editorconfig to configure severity. Otherwise, we continue using specified ruleset for configuration.
3. Updated the effective ruleset severity computation for the rule nodes under Analyzers node to account for severity settings from editorconfig (analyzer config documents).