anchor-spl with metadata feature fails to compile without token and associated_token

[lincot]

Running cargo build --no-default-features --features metadata results in a compilation failure because src/metadata.rs uses spl_token::ID and spl_associated_token_account::ID.

An easy way to fix this would be to make the metadata feature dependent on token and associated_token. However, adding associated_token introduces 71 new dependencies that are not always needed. A more efficient approach would be to define the program pubkeys directly.

[acheroncrypto]

Rather than hardcoding it ourselves, it might be better to use the new spl-associated-token-account-client crate which only depends on solana-program.

anchor-spl doesn't scale well because of problems like this one. Long term, I'm considering removing all its dependencies, or maybe even getting rid of anchor-spl altogether.