SwiftNIO 2.42.0 has deprecated Lock and replaced it with a new NIOLock. This commit removes all uses of Lock and replaces them with NIOLock. Further, now, we must require SwiftNIO 2.42.0
### Motivation
In #427 we switched the implementation over to our new `HTTPConnectionPool`. When we did this, we removed the possibility to access the requests underlying channel. For this reason we needed to remove a number of tests from `HTTPClientInternalTests`. As @weissi pointed out, we should at least still integration test downstream backpressure.
This pr replicates the behavior from `HTTPClientInternalTests.testUploadStreamingBackpressure` directly on the `HTTP1Connection`.
### Changes
- Move and adjust test from `HTTPClientInternalTests.testUploadStreamingBackpressure`
- Rename the test to `testDownloadStreamingBackpressure` since we only test incoming bytes backpressure.
### Result
An integration backpressure test, that survived #427.
- a new `RequestOptions` struct was created, that can be used to set request specific options. It is required by the `HTTPExecutableRequest`
- Added support for `ignoreUncleanSSLShutdown` in the `HTTPRequestStateMachine` and the `HTTP1ConnectionStateMachine`. In http/2 `ignoreUncleanSSLShutdown` is always off.
Fabian Fett