message: rpc: Add Coinstats index to getindexinfo
diff: #include <httpserver.h>
  #include <index/blockfilterindex.h>
  +#include <index/coinstatsindex.h>
  #include <index/txindex.h>
  #include <interfaces/chain.h>
  #include <interfaces/echo.h>
  @@ -729,6 +730,10 @@ static RPCHelpMan getindexinfo()
  result.pushKVs(SummaryToJSON(g_txindex->GetSummary(), index_name));
  }
  + if (g_coin_stats_index) {
  + result.pushKVs(SummaryToJSON(g_coin_stats_index->GetSummary(), index_name));
  + }
  +
  ForEachBlockFilterIndex([&result, &index_name](const BlockFilterIndex& index) {
  result.pushKVs(SummaryToJSON(index.GetSummary(), index_name));
  });
  