Feature: show plugins and clients in panel

[thewahome]

Overview

Closes #5715

Demo

Tasks

• When there are clients and plugins in the current context, Kiota should show the Workspace panel expanded and listing all clients and plugins available
• The "My workspace" panel must be in the top.
• When there is no clients or plugins in the context, the Workspace panel should load collapsed when opening Kiota extension.
• When there is no clients or plugins in the context and one expands the Workspace panel, we should show a "No clients or plugins are available" in the panel.
• Only show the Clients component when there is at least 1 client in the current context. If no client was found, the node shouldn't be displayed.
• Only show the Plugins component when there is at least 1 plugin in the current context. If no plugin was found, the node shouldn't be displayed.
• Clients and Plugins components must to be expandable/collapsible.
• When hovering the { } icon in any existing plugin/client, we should show the text Select. When clicking on it, the API Explorer should be loaded with the right client/plugin and right selected paths (same as the EditPaths codelense action)
• When hovering the trash icon in any existing plugin/client, we should show the text Delete. When clicking on it for any existing plugin/client, the plugin remove should be performed.

Future work

• the notification for regeneration should be displayed once an api is loaded.

[baywet]

also, now that we have a unit test infrastructure in place, we should make it a habit to include unit tests to get at least a basic coverage.

[baywet]

Thank you for making the changes!