Add SideShift.ai plugin

[szgergely]

This pull request adds SideShift.ai reporting functionality to the Edge partner revenue share reporter.

sideshiftAffiliateId and sideshiftAffiliateSecret can be obtained from the SideShift.ai affiliate page. They should be added to a new app document in the report-apps database as

{
  "appId": "sideshift",
  "pluginIds": {
    "sideshift": {
      "sideshiftAffiliateId": "",
      "sideshiftAffiliateSecret": ""
    }
  }
}

The reporter uses the SideShift.ai REST API /affiliate endpoint. It fetches the completed fixed rate orders made through Edge Wallet, processes them to an array of StandardTx objects and adds them to the reports-transactions database as a new document.

Accompanying pull requests:

• edge-exchange-plugins
• edge-react-gui