Merge dashpay#6052: refactor: use new type of composite commands for masternode NNN

64f3477 refactor: remove unused header spork.h from rpc/masternode (Konstantin Akimov)
43e9ab4 refactor: use new type of composite commands for masternode NNN (Konstantin Akimov)

Pull request description:

  ## Issue being fixed or feature implemented
  See dashpay#6051

  ## What was done?
  Commands starting from 'masternode ...' uses new a new way to make composite commands.

  ## How Has This Been Tested?
  Run unit/functional tests.
  Please notice, we support both styles `masternodelist` and `masternode list` which are still both supported.

  ## Breaking Changes
  N/A

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [x] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone

ACKs for top commit:
  PastaPastaPasta:
    utACK 64f3477

Tree-SHA512: 5a658588dff7f29d3025d2a720c8efe8096f79e8d632800911573f2f9a42450c2f27da070a94c5739e2027153413cdcacde82a7b4614467e036c008719692ed9

Author: PastaPastaPasta