Versioning the wallet_sc

Nobody has claimed this yet.

The deployed smart contract should have a clear version that links it to the source code from which it was compiled.

The TZIP-16 (https://tzip.tezosagora.org/proposal/tzip-16) describes a mechanism for adding metadata information to a deployed contract.

TLDR:
We need to do the following
- add a field name `metadata : (string, bytes) big_map` in the contract storage
- in the initial storage of the contract we need to fill the metadata map with an entry (key = "", value=""), where the `url-of-metadata-json` should be UTF-8 encoded

The accepted URLs are IPFS or HTTP/S+SHA256.

The metadata Json should look like this:
```
{
"name": "Chusai Wallet",
"description": "Contract to demo the interaction with Chusai optimistic rollup",
"homepage": "https://github.com/marigold-dev/chusai",
"authors": [
"https://github.com/orgs/marigold-dev/teams/chusai"
],
"interfaces": [
"TZIP-16"
],
"license": { "name": "@@LICENSE@@" },
"version": "@@VERSION@@",
"source": {
"tools": ["CamLIGO @@LIGO_VERSION@@"],
"location": " https://github.com/marigold/chusai/commit/@@COMMIT_HASH@@"
}
}
```