Function name casing

[erijo]

It would be nice if gersemi could be instructed to not always lower case function names, for cases where PascalCase is used instead of snake_case. E.g. official functions such as FetchContent_MakeAvailable() but also custom functions such as MyCoolFunction(). Either to maintain the casing used in the CMakeLists.txt or be able to enforce the casing used when the function is defined (or with a hint).