This is a cancellation token that cancels when any of its constituent
cancellation tokens are cancelled.
This token is used to fix a bug in Find Definitions. Previously, when
clicking `CTRL` (or `CMD` on macs) inside a source file in an archive
and hovering over a token, this will automatically invoke the
definitions finder (in preparation for navigating to the definition).
The only way to cancel is to move down to the message popup and click
cancel there.
However, this is a bug. What _should_ happen is that if a user moves
their mouse away from the token, the operation should cancel.
The underlying problem is that the extension was only listening to the
cancellation token from inside `getLocationsForUriString` the
cancellation token used by the Language Server protocol to cancel
operations in flight was being ignored.
This fix will ensure we are listening to _both_ cancellation tokens
and cancel the query if either are cancelled.
This will change the `AbstractWebview` to dispose its tracked objects
(using `this.push`) when the panel is disposed rather than when the
view is disposed. This makes `this.push` actually useful in a view.
Before, the objects would only get disposed when the extension itself
was disposed.
Previously, if there was an explicit restart of the query server (eg-
by changing a configuration setting), then the query server process
would be started twice: once by the `close` handler and once by the
restart command.
By adding the `removeAllListeners` to the dispose method, we ensure that
when the query server shuts down gracefully, there won't be a `close`
listener that is going to restart it a second time if there is a
different way of restarting it.
It seems like Node's native `fetch` implementation isn't quite working
right with Octokit and MSW. This switches to using `node-fetch` like
we're already doing for all other requests (e.g. downloading databases).
