Support stream resumption in stateless mode #1131
Description
There are some changes we need to make outside the implementation of ISseEventStreamStore. For example, in stateless mode, sessions currently get disposed immediately when the POST request completes. This causes the message processing loop to stop, which means new messages never reach the transport and never get written to the event stream store. So, we'd need to revisit the behavior around session lifetimes in stateless mode. I could probably do that in this PR, but it's already quite large and I figured leaving out stateless mode support for now could be a way to scope things down. If you think it should be included in this PR, I could go ahead and try to get it working.
Originally posted by @MackinnonBuck in #1077 (comment)