Fix scope source

[gabrielpra1]

• Remove scope: :source
• Change scope to scope_by in ObjectScopeAuthorization, using the returned struct as scope
• Change validations to require any struct instead of an Ecto schema
• Add meta :rule for FieldAuthorization
• Use source struct and scope_by for FieldAuthorization scoping
• Add meta :rule for ObjectScopeAuthorization
• Unify all scope functions in Rajska (no more context_field_authorized)
• Test queries that return primitives (e.g. :string)

[gabrielpra1]

@rschef We thought about using the same scope_by for Field and Object. However, now that we don't have meta :scope anymore, the meta scope_by is what defines if we are using ObjectScope or not:

# Using ObjectScope
object :user do
  meta :scope_by, :id
end

# ObjectScope not included in the application, no need to define anything
object :user do
end

# ObjectScope in the application, must be explict about not using scope 
object :user do
  meta :scope_by, false
end

What if we want FieldAuthorization for one object but not ObjectAuthorization?

[rschef]

@rschef We thought about using the same scope_by for Field and Object. However, now that we don't have meta :scope anymore, the meta scope_by is what defines if we are using ObjectScope or not:

# Using ObjectScope
object :user do
  meta :scope_by, :id
end

# ObjectScope not included in the application, no need to define anything
object :user do
end

# ObjectScope in the application, must be explict about not using scope 
object :user do
  meta :scope_by, false
end

What if we want FieldAuthorization for one object but not ObjectAuthorization?

We could have 3 meta options:

• scope_by for both field and object authorization
• scope_object_byfor object authorization
• scope_field_by for field authorization