Fix: kiota workspace tab correction

[thewahome]

Overview

Closes #5715

Also:

• I noticed that for items to load / refresh on the workspace tree, the workspace file needed to be open. This is no longer the case.
• When deleting a client/plugin that has been opened in the API Explorer, it is closed first then deleted to remove any chance for unparented explorer items

Demo

Notes:

Can't fix When there is no clients or plugins in the context, the Workspace panel should load collapsed when opening Kiota extension because VS Code does not provide a direct way to set the collapsed state of a view container through the package.json configuration. And programmatically changing it has not worked