standardize client config

[emeceve]

Create a NIP that standardize the config file that is up to the client give support or not.

An initial scheme idea:

{
   "user":{
      "name":"string",
      "about":"string",
      "picture_url":"string",
      "public_key":"string",
      "secrets":{
         "secret_key":"string",
         "seed_phrase":"string"
      },
      "contacts":[
         {
            "public_key":"string",
            "alias":"string"
         }
      ],
      "relays":[
         {
            "url":"string",
            "permissions":{
               "write":"bool",
               "read":"bool"
            }
         }
      ]
   }
}

All the content in field secrets MUST be encrypted OR empty.

Some references for secrets encryption:

Wasabi implementation AES Encryption with HMAC Integrity in Java