Allow notebook extensions run in dedicated extension host

[rebornix]

This is an attempt to run notebook extensions in a dedicated extension host without being affected by other extensions (or vice versa). In the changes, I spawned another LocalExtensionHost for notebook extensions. As @alexdima pointed out, it adds notebook knowledge to the extension service. A better approach is that extension service allow others to register filters (then the notebook component can register a filter for notebook extensions) and extension meet the filter can be grouped into a new extension host.

[alexdima]

@rebornix I've just merged #144840 . You can now use:

"extensions.experimental.affinity": {
   "ms-toolsai.jupyter": 1
}

This will move the extension together with all dependencies or dependents to a separate extension host.

[alexdima]

@rebornix I suggest to close this out in favor of #144840 . Please give it a try and let me know if it works for the Notebooks use-case.

[rebornix]

Thanks @alexdima , will give it a try today!