decoder/ffmpeg: make the tag_table constexpr
ConfigParser: make the static arrays "const"
AllCommands: use ARRAY_SIZE()
decoder/mad: convert "const" to "constexpr"
ls: make the static array "const"
output/oss: make the static arrays "constexpr"
ConfigTemplates: use ARRAY_SIZE()
DespotifyUtils: use ARRAY_SIZE()
DespotifyUtils: fix coding style
DespotifyUtils: make string buffers temporary