Remove scopes validation from alchemiscale compute synchronous CLI endpoint; enforce as validator in ComputeServiceSettings

[dotsdl]

Since we are now using a pydantic model for compute service settings (ComputeServiceSettings), we can enforce a certain form for data elements using validators.

We should add a validator for scopes that allows giving them in string form. If given in that form, it should turn them into Scopes via Scope.from_str.

We can then remove external transformations currently performed in the CLI entrypoint alchemiscale compute synchronous, as well as elsewhere for other compute service implementations (such as in alchemiscale-fah).