set SDLMIXER_VENDORED to ON and vendor the required libraries into libs/SDL3_mixer/external

disable SDLMIXER_VORBIS_VORBISFILE
add ogg v1.3.5-SDL
add opus v1.4.x-SDL
add opusfile v0.13-git-SDL

libs/SDL3_mixer/external/ogg/.gitignore

@@ -0,0 +1,50 @@
+aclocal.m4
+autom4te.cache
+ChangeLog
+compile
+config.guess
+config.h
+config.h.in
+config.h.in~
+config.log
+config.status
+config.sub
+configure
+depcomp
+install-sh
+libogg.spec
+libtool
+ltmain.sh
+Makefile
+Makefile.in
+missing
+mkinstalldirs
+ogg.pc
+ogg-uninstalled.pc
+stamp-h1
+.project
+include/ogg/config_types.h
+src/*.o
+src/*.lo
+src/lib*.la
+src/.libs
+src/.deps
+src/test_*
+macosx/build/
+/m4
+
+CMakeCache.txt
+CMakeFiles
+CMakeScripts
+Testing
+Makefile
+cmake_install.cmake
+install_manifest.txt
+compile_commands.json
+CTestTestfile.cmake
+CMakeSettings.json
+
+*[Bb]uild*/
+
+.vs/
+.vscode/