protobufjs 7.0.0 removes pbjs

[jroper]

We depend on pbjs for some things. protobufjs 7.0.0 has been released, and doesn't contain this, a new package, protobufjs-cli, contains it. I think our dependency on protobufjs is a minimum version so we may find users being automatically upgraded to this, and then protobuf compilation will break saying pbjs or pbts can't be found.

See protobufjs/protobuf.js#1773

[pvlugter]

Could be an opportunity to move the protobuf compilation to kalix-scripts, along with the other dev and codegen tooling. Will then be only a dev dependency on protobufjs-cli.

Good that a new version of protobufjs is finally out though, as it allows #326.