### Motivation
Fixes#238 and #231.
### Changes
- Extracted the unclean shutdown test from `HTTPClientTests` into their own file `HTTPClientUncleanSSLConnectionShutdownTests`
- Copy and pasted @weissi great explanation from #238 into the test file
- Removed property `ignoreUncleanSSLShutdown` everywhere
### Result
`ignoreUncleanSSLShutdown` on `HTTPClient.Configuration` is deprecated and ignored.
Co-authored-by: Johannes Weiss <johannesweiss@apple.com>