Add a test to demonstrate connection logical deadlock due assigning capacity to pending open streams #863
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This is a companion PR to help understand the bug pointed out by PR #860.
The program I present here is based on PR #852, which also demonstrates a deadlock. However, according to my research, these two examples deadlock for entirely different reasons. While PR #852 deadlocks due to not calling flow capacity methods, the program I present here DOES, afaik, correctly call flow capacity methods.
The test presented here sends requests and responses in chunks, and due to that, triggers a deadlock because the client ends up assigning stream capacity to streams that are still in the pending_open state. Once the client assigns all of the connection capacity to streams that are in pending_open, the entire program deadlocks as nothing can make progress.
The deadlock in this program is fixed by PR #860.