fix(codegen): allow using x-go-type and x-go-type-skip-optional-pointer together

[Nivl]

When using x-go-type, GenerateGoSchema returns early, meaning that any extensions that are checked after this one are no-op.

This PR moves the code for x-go-type-skip-optional-pointer higher up, so it can be used alongside x-go-type.

This PR only fixes a bug, not the root issue. There may be more similar issues, and the code makes it easy to introduce new similar bugs. Ultimately we'd need to refactor GenerateGoSchema to:

1. Add tests
2. Not return early (to avoid having the same issue on). We return early at multiple places in this method.

This isn't the goal of that PR though, so maybe in another one.

[jamietanna]

Thanks! Will take a look hopefully today, and see if I can get some tests added to cover this

[jamietanna]

Do you have an example (minimal spec) that this change improves the codegen for? In my limited testing, I can't seem to get much meaningfully different when applying this PR

I can see that looking a this with an allOf does actually provide some differences in the generated code for a case I'm interested in, but can't seem to see this PR as-is changing much, but maybe I'm missing something?

[Nivl]

With this

paths:
  /root:
    get:
      operationId: getRoot
      parameters:
        - in: query
          name: at
          schema:
            type: string
            format: date-time
            x-go-type-skip-optional-pointer: true
            x-go-type: pgtype.Timestamptz
            x-go-type-import:
              path: github.com/jackc/pgx/v5/pgtype
              name: pgtype

      responses:
        "200":
          description: Some data

I expect something like that:

type GetRootParams struct {
	At pgtype.Timestamptz `form:"at,omitempty" json:"at,omitempty"`
}

instead of

type GetRootParams struct {
	At *pgtype.Timestamptz `form:"at,omitempty" json:"at,omitempty"`
}

Currently, If I remove all the x-go- stuff I get:

type GetRootParams struct {
	At *time.Time `form:"at,omitempty" json:"at,omitempty"`
}

Which is correct.
if I set x-go-type-skip-optional-pointer: true I get

type GetRootParams struct {
	At time.Time `form:"at,omitempty" json:"at,omitempty"`
}

Which is also correct.
If I set

            x-go-type: pgtype.Timestamptz
            x-go-type-import:
              path: github.com/jackc/pgx/v5/pgtype
              name: pgtype

I get

type GetRootParams struct {
	At *pgtype.Timestamptz `form:"at,omitempty" json:"at,omitempty"`
}

Which is still correct.
But if I set both:

            x-go-type-skip-optional-pointer: true
            x-go-type: pgtype.Timestamptz
            x-go-type-import:
              path: github.com/jackc/pgx/v5/pgtype
              name: pgtype

I get:

type GetRootParams struct {
	At *pgtype.Timestamptz `form:"at,omitempty" json:"at,omitempty"`
}

Which is incorrect.

This PR should be fixing that, and makes sure we're not using a pointer when x-go-type-skip-optional-pointer is set to true.