Define a Scalar
# Macro attributes
| Attribute | description | Type | Optional |
|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------|
| name | Scalar name | string | Y |
| specified_by_url | Provide a specification URL for this scalar type, it must link to a human-readable specification of the data format, serialization and coercion rules for this scalar. | string | Y |
| inaccessible | Indicate that a scalar is not accessible from a supergraph when using Apollo Federation | bool | Y |
| tag | Arbitrary string metadata that will be propagated to the supergraph when using Apollo Federation. This attribute is repeatable | string | Y |