Surface deprecation fields in Error Objects for Validate

[samchungy]

Is your feature request related to a problem? Please describe.

Firstly big thanks for your repo :)

Secondly,

I would like to populate ${parentType.name}.${fieldDef.name} into the GraphQLError Extensions so I can retrieve it via error.extensions without needing to regex on the string.

graphql-inspector/packages/core/src/utils/graphql.ts

Line 141 in ca8e7cd

`The field '${parentType.name}.${fieldDef.name}' is deprecated.${reason ? ' ' + reason : ''}`,

Describe the solution you'd like

I would like to be able to access deprecations via the error object's extensions.

eg. to access the field via error.extensions.field

Describe alternatives you've considered

Running Regex on the string to pull the path. Seems a bit hacky when the info is right there.