chore: add tests for input highlighting (#6779)

Reviewed-by: Arne <78976058+4rneee@users.noreply.github.com>
Reviewed-by: pajlada <rasmus.karlsson@pajlada.com>

tests/CMakeLists.txt

@@ -60,6 +60,7 @@ set(test_SOURCES
     ${CMAKE_CURRENT_LIST_DIR}/src/TwitchChannel.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/TwitchUserColor.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/FunctionRef.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/InputHighlighter.cpp
 
     ${CMAKE_CURRENT_LIST_DIR}/src/lib/Snapshot.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/lib/Snapshot.hpp