[Fusion] Fixed duplicated selections

[tobias-tengler]

Fixes #7687

[tobias-tengler]

Just noticed another issue that has also existed previously: Selections on interfaces are inlined into object type selections, but not explicitly forwarded to subgraphs.

Original query:

communityItems(first: 3) {
  nodes {
    __typename
    ... on CommunityDiscussion {
      databaseId
    }
    ... on ProductQuestion {
      databaseId
    }
    ... on ProductReview {
      databaseId
    }
    ... on Node {
      __isNode: __typename
      id
    }
  }
}

Subgraph query:

communityItems(first: 3) {
  nodes {
    __typename
    ... on CommunityDiscussion {
      __typename
      databaseId
      __isNode: __typename
      id
    }
    ... on ProductQuestion {
      __typename
      databaseId
      __isNode: __typename
      id
    }
    ... on ProductReview {
      __typename
      databaseId
      __isNode: __typename
      id
    }
  }
}

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.00%. Comparing base (02b1ca8) to head (1121c64). Report is 34 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #7677 +/- ## ========================================== + Coverage 73.95% 74.00% +0.05% ========================================== Files 2917 2918 +1 Lines 151116 151252 +136 Branches 17560 17576 +16 ========================================== + Hits 111753 111936 +183 + Misses 33507 33465 -42 + Partials 5856 5851 -5 ``` | [Flag](https://app.codecov.io/gh/ChilliCream/graphql-platform/pull/7677/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ChilliCream) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ChilliCream/graphql-platform/pull/7677/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ChilliCream) | `74.00% <ø> (+0.05%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ChilliCream#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.