Add missing staking ledgers to REST summary

[Isaac-DeFrain]

Example: "missingStakingLedgers": [17, 18, 19]

{
  "blockchainLength": 99999,
  "chainId": "5f704cc0c82e0ed70e873f0893d7e06f148524e3f0bdae2afb02e7819a0c24d1",
  "circulatingSupply": "350083645.840039233",
  "dateTime": "Sat, 15 Jan 2022 19:51:00 GMT",
  "epoch": 20,
  "slot": 3517,
  "globalSlot": 146317,
  "lockedSupply": "535677087",
  "minWindowDensity": 19,
  "nextEpochLedgerHash": "jxix1ap5gwXmiiwRqjijDv5KbHmnjAfj19CDywRLT1J8yTADcsT",
  "previousStateHash": "3NKfk3kXzoe24vvsiChZCrwAXULQ7DrouisoZQmcouhJ4Nyx9yNT",
  "snarkedLedgerHash": "jxwSSaTgKr31McYoLmL6aEgw1rLWi1EW4pCkeECuRkFQaGuw9nk",
  "stagedLedgerHash": "jwXnWXPute1hW6vjNMGuYHVXEAYumNN4j8qVDp3irtq12RDds7o",
  "stakingEpochLedgerHash": "jxBBSjakhQRKLbUM7z99KXNnMke2GbdcJyqpD9gyRoJJybsMRqh",
  "stateHash": "3NLybqcnQ58MqhUjeKUkk3uXAv93xikCGkfsGMnkQENcmeH2Xx7i",
  "totalCurrency": "885760732.840039233",
  "totalNumAccounts": 87948,
  "epochNumBlocks": 4434,
  "totalNumBlocks": 219331,
  "epochNumSnarks": 59096,
  "totalNumSnarks": 1833391,
  "epochNumUserCommands": 85749,
  "totalNumUserCommands": 2779411,
  "epochNumInternalCommands": 31701,
  "totalNumInternalCommands": 1566372,
  "dbVersion": "0.5.0-ee3e6eef",
  "indexerVersion": "0.1.1-ee3e6eef"
  "missingStakingLedgers": [17, 18, 19]
}