Remove workflow inspector, clean up workflow code (#16325)

Now that there's a dedicated, user-facing view for each workflow step,
we don't need the inspector functionality. This PR also cleans up some
naming around workflow steps and step resolutions.

Release Notes:

- N/A

crates/assistant/src/assistant.rs

@@ -3,7 +3,6 @@
 pub mod assistant_panel;
 pub mod assistant_settings;
 mod context;
-pub(crate) mod context_inspector;
 pub mod context_store;
 mod inline_assistant;
 mod model_selector;
@@ -65,7 +64,6 @@ actions!(
         DeployPromptLibrary,
         ConfirmCommand,
         ToggleModelSelector,
-        DebugWorkflowSteps
     ]
 );