feat: add initial experimental Twitch Eventsub support (#5837)

Co-authored-by: nerix <nerixdev@outlook.de>

CMakeLists.txt

@@ -207,6 +207,7 @@ find_package(PajladaSignals REQUIRED)
 find_package(LRUCache REQUIRED)
 find_package(MagicEnum REQUIRED)
 find_package(Doxygen)
+find_package(BoostCertify REQUIRED)
 
 if (USE_SYSTEM_PAJLADA_SETTINGS)
     find_package(PajladaSettings REQUIRED)
@@ -229,6 +230,8 @@ if (BUILD_WITH_CRASHPAD)
     add_subdirectory("${CMAKE_SOURCE_DIR}/tools/crash-handler")
 endif()
 
+add_subdirectory(lib/twitch-eventsub-ws EXCLUDE_FROM_ALL)
+
 # Used to provide a date of build in the About page (for nightly builds). Getting the actual time of
 # compilation in CMake is a more involved, as documented in https://stackoverflow.com/q/24292898.
 # For CI runs, however, the date of build file generation should be consistent with the date of