Openrct2: (Source) file names are not unique

[janisozaur]

Some tools require unique file names for source files. We have some clashes in the repository.

File names should be made unique and there should be a CI check to verify that holds.

$ git ls-files | grep src/.\*\\\.c | xargs -n1 basename | sort | uniq -d
AudioMixer.cpp
Banner.cpp
input.c
peep.c
scenery.c
ServerList.cpp
sprite.c

$ for i in $(git ls-files | grep src/.\*\\\.c | xargs -n1 basename | sort | uniq -d) ; do git ls-files | grep \\\<$i\\\> ; done
src/openrct2-ui/audio/AudioMixer.cpp
src/openrct2/audio/AudioMixer.cpp
src/openrct2/windows/Banner.cpp
src/openrct2/world/Banner.cpp
src/openrct2-ui/input/input.c
src/openrct2/input.c
src/openrct2/paint/sprite/peep.c
src/openrct2/peep/peep.c
src/openrct2/paint/map_element/scenery.c
src/openrct2/world/scenery.c
src/openrct2-ui/windows/ServerList.cpp
src/openrct2/network/ServerList.cpp
src/openrct2/paint/sprite/sprite.c
src/openrct2/world/sprite.c

[Gymnasiast]

I don't think it's a very good idea to mess up our file names, just because some tools are apparently so badly written they cannot handle this.