Refactor instance module to cosmos style

[krhubert]

Dep: #1651

Please note that passing cosmos client to service or process sdk is just a temporary solution until all modules will move to x dir/

[NicolasMahe]

the command instance get doesn't work:

➜  engine git:(refactor/cosmos-instance-module) ./bin/mesg-cli query instance get 8sYvgq4TqzZo7cdyMqR7fYKbUvvhXbecMcSBcBjjuYSF
could not get instance
ABCIQuery: RPC error -32603 - Internal error: runtime error: index out of range [0] with length 0

the hash is correct:

➜  engine git:(refactor/cosmos-instance-module) ./bin/mesg-cli query instance list
[{"hash":"8sYvgq4TqzZo7cdyMqR7fYKbUvvhXbecMcSBcBjjuYSF","serviceHash":"8P4Dm57fr8EFA4HQ4XK8rMnQcc4De6eDxSD5bHZ5oKWW","envHash":"6LfKoQQMqb8fYgA1PwBPKMhFaJ59Fn3DWw6qTRri4zjN"}]

---

same issue with rest:

➜  engine git:(refactor/cosmos-instance-module) curl 127.0.0.1:1317/instance/get
{
  "jsonrpc": "2.0",
  "id": -1,
  "error": {
    "code": -32603,
    "message": "Internal error",
    "data": "runtime error: index out of range [0] with length 0"
  }
}
➜  engine git:(refactor/cosmos-instance-module) curl 127.0.0.1:1317/instance/get/8sYvgq4TqzZo7cdyMqR7fYKbUvvhXbecMcSBcBjjuYSF
404 page not found

it's look like you try to use one function for both endpoint:
https://github.com/mesg-foundation/engine/pull/1653/files#diff-87961d244ba475f23c501d75dee36448R13-R46
let's create one function per endpoint for now like other cosmos module:
https://github.com/cosmos/cosmos-sdk/blob/master/x/mint/client/rest/query.go