When @link multiple subgraphs the @server port is overwritten from the last schema

[karatakis]

Prerequisites

• I have checked the existing issues to ensure this is not a duplicate.
• I am running the latest version of Tailcall.

Describe the bug

When @link multiple subgraphs, the @server port from the main file is overwritten from the last schema.

Steps to reproduce

main.graphql

schema
  @link(type: Config, src: "./a.graphql")
  @link(type: Config, src: "./b.graphql")
  @server(port: 8080)
  @upstream {
  query: Query
}

type Query {
  main_version: Int! @expr(body: 1)
}

a.graphql

schema
  @server(port: 8081)
  @upstream {
  query: Query
}

type Query {
  a_version: Int! @expr(body: 1)
}

b.graphql

schema
  @server(port: 8082)
  @upstream {
  query: Query
}

type Query {
  b_version: Int! @expr(body: 1)
}

Expected behavior

The server should listen on port 8080

Actual behavior

The server listens at 8082

[ssddOnTop]

it's because of our current merge_right implementation https://github.com/tailcallhq/tailcall/blob/a46a773f8a56fd2b9a22ec67dd4fd12d4415d266/src/core/merge_right.rs#L9C1-L19C1

we probably shouldn't directly implement merge right for Option<u16> as config::Server has pub port: Option<u16>