Add ability to filter by releases on Boards through GraphQL

Need to add the token to GraphQL filtered search. This is currently available for Boards with the following query:

fragment ReleaseFilters on BoardList{
  issues(filters: { releaseTag: "release" }){
    nodes
  }
}

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Feature Flag

We're working on refactoring filtered search on boards to use GraphQL. This issue is part of that work, and is behind the :issue_boards_filtered_search feature flag.