Avoid holding locks in winhttp_http_task completion callback handling…

… when calling into websocket event functions (microsoft#580)

* Move winhttp_http_task completion_callback lock handling into the individual callback type handlers to avoid holding onto lock when calling into externally provided event handlers

* Move duplicate XAsyncComplete checking to compete_task

* tabs -> spaces

* don't hold lock for complete_task since it can call back into client code synchronously

found that project IDs were in conflict across other projects that in…

…clude libHttpClient -- somewhere the project IDs got corrupted through a merge or something. (microsoft#487)

Fixup the 2019 solution (microsoft#483)

Build/libHttpClient.Apple.C/libHttpClient.xcodeproj/project.pbxproj