Roon:Map PERFORMER to PERFORMER fields for all formats, add INVOLVEDPEOPLE for all formats except for ID3 map to TIPL/IPLS

[IJabz]

Roon, expects PERFORMER to be primary artist so if you use FieldKey.PERFORMER for all formats Roon will add as primary artist rather than secondary artist credit except for ID3 format because for ID3 FieldKey.PERFORMER maps to TIPL/IPLS which is correct and what Roon works with.

To fix this we want all other formats to use INVOLVEDPEOPLE field instead of PERFORMER field. So for consistency need to create new FieldKey.INVOLVEDPEOPLE and map to INVOLVEDPEOPLE for all formats except for ID3 where it should map to TIPL/IPLS

Then existing FieldKey.PERFORMER key should map to PERFORMER for all fields, currently it does except for ID3 where it needs modifying.

Note existing FieldKey.INVOLVED_PERSON should be removed as just confuses, and just keep Mp4FieldKey.INVOLVED_PERSON since this is the only mapping to a real field otherwise not covered (peop)

[IJabz]

There is additional confusion that in ID3v24 we have both TIPL and TMCL but for v22 and v23 we dont (only IPLS), also don't think ROON recognizes MUSICIANCREDITS field in Flac. So ideally would like to store musician credits in TMCL and other credits in TIPL but seems only ID3v24 supports this in a way that Roon can read, therefore easier to just ignore existence of MusicianCredits tag for all formats, for now.

[IJabz]

Done.