Escape should cancel in-flight completion request

[MinusGix]

When typing, you sometimes know that you'll get completion but you know you won't need it. Currently you can wait for the completion to appear (it might take half a second on a large project) and then press escape but that isn't as nice.
This would be a minor usability improvement because it would mean you don't have to stall out as much while typing.

[dmanias]

I use the 0.2 version in Ubuntu 22.04 LTS . I don't see the in-flight completion. Should I activate it?

[RaresAndrei0]

I was not able to reproduce the problem, but a possible fix might be modifying the cancel() method in completion.rs to add self.request_id += 1;. The response gets rejected immediately in the recieve() function because self.request_id != request_id.
I will open a pull request and see how it is received.