draft: adding handler to return all assets of an account

[barnjamin]

Summary

A half attempt at an endpoint to support

#5250

Mostly because I was curious about what it would take and to serve as a subject for discussion

If we were to pursue this approach we'd probably want to at least

1. remove the /0 in the path so that the endpoint is just /v2/accounts/{address}/assets
2. tweak the returned data to have a more appropriate wrapper type

If performance of this endpoint is a concern, we could add it to one of the flagged off set of handlers

Test Plan

copied the bin into my sandbox and ran a curl

curl localhost:4001/v2/accounts/AZRSDXCKQIUKIEEFF7FMF43ZNTFWCYONKAI3SXX5GRVPURLMTXI2OVSKUY/assets/0  -H "X-Algo-API-Token: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"

returns

[
  {
    "asset-holding": {
      "amount": 10,
      "asset-id": 220,
      "is-frozen": false
    },
    "created-asset": {
      "clawback": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "creator": "AZRSDXCKQIUKIEEFF7FMF43ZNTFWCYONKAI3SXX5GRVPURLMTXI2OVSKUY",
      "decimals": 0,
      "default-frozen": false,
      "freeze": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "manager": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "name": "lol",
      "name-b64": "bG9s",
      "reserve": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "total": 10000
    },
    "round": 0
  },
  {
    "asset-holding": {
      "amount": 10,
      "asset-id": 223,
      "is-frozen": false
    },
    "created-asset": {
      "clawback": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "creator": "AZRSDXCKQIUKIEEFF7FMF43ZNTFWCYONKAI3SXX5GRVPURLMTXI2OVSKUY",
      "decimals": 0,
      "default-frozen": false,
      "freeze": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "manager": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "name": "lmao",
      "name-b64": "bG1hbw==",
      "reserve": "R2MEJY67MKV6JDO7L6HXXONDGQPQJLXL6PSWZONO67ZAC76QTHSIZ54NHI",
      "total": 10000
    },
    "round": 0
  }
]