Fixes#330

Adds a search filter for both views "My Workspaces" and "All Workspaces", this depends on the VS Code commandlist.find so support fuzzy match and filtering but does not differentiate between nodes (so we filter on everything not just workspaces or agents... etc).

Also, I have addids to all tree items, this guarantees that the expansion state stays the same between refreshes.

One downside to using this method is that whenever the tree view refreshes (which is every ~1s) the focus is shifted to the tree instead of the input. I tried to implement selective refreshing such that we refresh only the affected nodes but that didn't fix it :/. See: