feat!: support for NStorageMaps

[TarikGul]

closes: #811

Breaking Change - /pallets/{palletid}/storage/{storageId}

The current endpoint accepts two query parameters key1, and key2. It is now updated to accept an array query param called keys that accepts and N amount of keys. ORDER MATTERS. The order in which the keys are inputted is the order they will be inputted into the storage query.

Example:
/pallets/Staking/storage/ErasValidatorPrefs?keys[]=0x00&keys[]=0x01

The response will no longer have key1 and key2 but will now have a keys field that returns an array of the keys..

Example:

{
  "at": {
    "hash": "0x7b713de604a99857f6c25eacc115a4f28d2611a23d9ddff99ab0e4f1c17a8578",
    "height": "789629"
  },
  "pallet": "staking",
  "palletIndex": "15",
  "storageItem": "erasValidatorPrefs",
  "keys": ["0x00", "0x01"],
  "value": ...
}

Changes (notes) - /pallets/{palletid}/storage/{storageId}

Query Params

Removed:
key1 and key2

Added - Order matters
keys - Needs to be formatted like: ?keys[]=<key1>&keys[]=<key2>&keys[]=<key3>

Response

Removed:
key1 and key2

Added
keys - Array

Todo

• Docs

[CurlyBracketEffect]

Like watching a skilled surgeon at work. Just have that one question about the 'unkown' values.

[marshacb]

lgtm!