RFC Arguments by default

[SerafimArts]

Adding default arguments for Fields and Inputs will require syntactic change of the GraphQL queries, so at the run-in phase, the features are enough to implement them at the Directive level.

Usage:

directive @route(action: String! @default) on OBJECT | FIELD 
                                # ^^^^^  Adding "@default" directive

type Query {
    users: [User]! @route("ExampleController@usersAction")
                       # ^^^ Use an optional argument name 
}

Instead of:

directive @route(action: String!) on OBJECT | FIELD 

type Query {
    users: [User]! @route(action: "ExampleController@usersAction")
                        # ^^^^^^  Explicit specification of the argument
}