LibMedia: Use FFmpeg to decode more video formats

VP9 continues to function, but this also allows AV1 to be decoded. With
this commit, H.264 is still non-functional, as the decoder requires
some extra initial data from the track definition in the Matroska file.

Meta/CMake/lagom_compile_options.cmake

@@ -21,6 +21,10 @@ if (LINUX)
     add_compile_options(-D_FILE_OFFSET_BITS=64)
 endif()
 
+if (APPLE)
+    list(APPEND CMAKE_PREFIX_PATH /opt/homebrew)
+endif()
+
 if (CMAKE_BUILD_TYPE STREQUAL "Debug")
     if (NOT MSVC)
         add_compile_options(-ggdb3)