chore: point chalk-integration to new salsa

[davidbarsky]

Kind of a boring change, but we need this in order to migrate rust-analyzer to the new Salsa (see: https://rust-lang.zulipchat.com/#narrow/channel/185405-t-compiler.2Frust-analyzer/topic/Porting.20to.20Salsa.203.2E0/near/487299583) and, eventually, off Chalk onto the new trait solver.

(Please hold off on merging this until salsa-rs/salsa#623 lands and https://github.com/davidbarsky/db-ext-macro/ is published.)

[jackh726]

I don't think we should accept this until there's a published release on crates.io (though, not sure why rust-analyzer would need this)