Make hover actions keyboard accessible

Hide cell output in webview when fold

This also adds a `availableEditors` context key that consists of a comma seperated list of editor ids that can be used for `reopen with`

Fixes #94673

* Add SyncActionDescriptor.from

There are a whole lot of places in our code where have the following pattern:

```
actionRegistry.registerWorkbenchAction(SyncActionDescriptor.create(CreateNewLocalTerminalAction, CreateNewLocalTerminalAction.ID, CreateNewLocalTerminalAction.LABEL));
```

Notice how the class name has to be repeated  three times.

This change introduces a helper function `SyncActionDescriptor.from` that lets you instead just pass in the class:

```js
actionRegistry.registerWorkbenchAction(SyncActionDescriptor.create(CreateNewLocalTerminalAction));
```

* Avoid cast

fixes #88230

#88230

Make environment variable widget screen reader and keyboard accessible

specific condicon names (WIP)