Better Artist Identity

[musnit]

It turns out that on nina, our assumption that a solana address corresponds to an artist address is incorrect. This is usually true, but in a few cases, record labels may use their address to create for multiple different artists.

This is apparent on Nina (eg: https://app.spinamp.xyz/artist/waxfactor), but likely also the case in some scenarios on Ethereum.

I think fixing this will be tied to other future tasks related to supporting multiple artists on a given track, and merging artist profiles across chains/platforms, so this issue is just here to document the concern overall.