Add Android Media Solutions to SettingsLib aconfig OWNERS

Bug: 205124386
Change-Id: I4a96d41cee9b41ea9eaaa295e7a9bbef5b78cd12
Test: N/A

packages/SettingsLib/aconfig/OWNERS

+# go/android-fwk-media-solutions for info on areas of ownership.
+per-file settingslib_media_flag_declarations.aconfig = file:platform/frameworks/av:/media/janitors/media_solutions_OWNERS