Support ability to add field options to generated protobuf

[joshua-bell-sonrai]

Reason

It would be nice if the ability to add custom field options.

Example

input

Config:
    type: object
    required:
      - config
    properties:
      config:
        type: string
        fieldOption: [ (graphqlOverride) = { type: "DateTime" } ]

output

message Config {
    string config = 1 [ (graphqlOverride) = { type: "DateTime" } ];
}