fix!: change the response for vesting-info

[TarikGul]

BREAKING CHANGE

With runtime v9110, the vesting-info response now returns an array for vesting, with the VestingInfo type now being Vec<PalletVestingVestingInfo>. Sidecar previously returned responses under the vesting key as objects, therefore when there was no information the response was an empty object.

This is now changed as the response will default to an empty array when there is no vesting-info on the account, and the past responses that were objects, will now be wrapped in an array.

Examples:

Before:

{
  "at": {
    "hash": "0x89f4608b568a05a89737bc826a32f8677f2646a5773312d7dee3a667458e5a98",
    "height": "6000000"
  },
  "vesting": {
      "locked": "1749990000000000",
      "perBlock": "166475460",
      "startingBlock": "4961000"
    }
}

After

{
  "at": {
    "hash": "0x89f4608b568a05a89737bc826a32f8677f2646a5773312d7dee3a667458e5a98",
    "height": "6000000"
  },
  "vesting": [
    {
      "locked": "1749990000000000",
      "perBlock": "166475460",
      "startingBlock": "4961000"
    }
  ]
}

[TarikGul]

This PR will be followed up by #709

[maciejhirsz]

Tiny nit

[maciejhirsz]

Would like to avoid double unwrap here, but not sure what a good way would be, TS would likely scream about something like:

Suggested change

	: Array.isArray(vesting.unwrap())
	? vesting.unwrap()
	: [vesting.unwrap()],
	: Array.isArray(vesting = vesting.unwrap())
	? vesting
	: [vesting],

Could use a different variable for the unwrapped value (declared before the return, assigned in place)? 🤔

[TarikGul]

Ahh very good point. I should have noticed that earlier when I tried to abstract the vesting.unwrap() before calling vesting.isNone which caused me issues.

Good call. Going to declare 2 variables, one for the bool value, and the other to unwrap vesting

[TarikGul]

So I actually changed it quiet a bit to isolate each case more, it avoids unwrapping if isNone is true and also avoids unwrapping multiple times as well.

[dvdplm]

Optimizing for clarity, I like it.