Add epics filters to epic board lists

What does this MR do?

Allows passing epic_filters attribute when to the epic board list which is then used for evaluating epicsCount field. Sample query:

query {
  group(fullPath: "h5bp") {
    id
    epicBoards {
      nodes {
        id
        name
        lists(id: "gid://gitlab/Boards::EpicList/3", epicFilters: {labelName: ["Afterbalt"]}) {
          nodes {
            id
            epicsCount
          }
        }
      }
    }
  }
}

Related to #328875 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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