Fix directives on fields with custom scalars

[enjoylife]

The bug occurs when using a custom defined scalar, an input type, and directive together.
E.g.

#schema.gql
scalar UUID
directive @direc(s: String!) on FIELD_DEFINITION | ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION
input CustomInput {
    stuff:[UUID]  @direc(s:"stuff")
}

// custom models
import "github.com/gofrs/uuid"
func MarshalUUID(id uuid.UUID) graphql.Marshaler{ /* ... */ }
func UnmarshalUUID(input interface{}) (uuid.UUID, error) { /* ... */ }

would generate:

// ...
// shouldn't be whole path of github.com/gofrs/...
if data, ok := tmp.([]*github.com/gofrs/uuid.UUID) ; ok {
    it.Stuff = data
} else {
    return it, fmt.Errorf(`unexpected type %T from directive, should be []*github.com/gofrs/uuid.UUID`, tmp)
}

now:

if data, ok := tmp.([]*uuid.UUID); ok {
    it.Stuff = data
} else {
    return it, fmt.Errorf(`unexpected type %T from directive, should be []*github.com/gofrs/uuid.UUID`, tmp)
}

[vektah]

Needs a test

[enjoylife]

Added to the integration schema such that it will catch said bug during go generate.

Prior to diff running go generate with the added schema:

❯ go generate ./...
gofmt failed on generated.go: /Users/matt/Projects/gqlgen/codegen/testserver/generated.go:3856:37: expected ')', found '/' (and 5 more errors)
Generated github.com/99designs/gqlgen/codegen/testserver in 1.23s
Generated github.com/99designs/gqlgen/example/chat in 1.04s
Generated github.com/99designs/gqlgen/example/config in 1.04s
Generated github.com/99designs/gqlgen/example/dataloader in 1.33s
Generated github.com/99designs/gqlgen/example/scalars in 1.18s
Generated github.com/99designs/gqlgen/example/selection in 1.03s
Generated github.com/99designs/gqlgen/example/starwars in 1.15s
Generated github.com/99designs/gqlgen/example/todo in 1.17s
Generated github.com/99designs/gqlgen/example/type-system-extension in 1.08s
Generated github.com/99designs/gqlgen/integration in 1.24s

After diff it builds fine. @vektah I'm hoping that would cover the "test" ask? If not, I would need some guidance on what would be a good example test to follow/improve.

[enjoylife]

Not sure if the failure is from me force pushing or something else as it just works local.

[vektah]

After diff it builds fine. @vektah I'm hoping that would cover the "test" ask? If not, I would need some guidance on what would be a good example test to follow/improve.

Yeah, that looks good. As long as it cant happen again without something breaking. Most of the templates are covered like this.

Not sure if the failure is from me force pushing or something else as it just works local.

Its failing because you've changed the testserver schema but havent run go generate ./... and committed the changes.

[vektah]

I see, looks like theres some instability in the generated code. It looks unrelated to this change so Ill fix it on next.