[ANCHOR-809] Add sep31 methods to asset config and info response

[JiahuiWho]

Description

Add methods to sep31.receive in asset config per discussion.

Also add methods to Sep31InfoResponse. To keep consistency of the sep info response, new SEP-31 response will be look like this:

  {
    "receive": {
      "JPYC": {
        "enabled": true,
        "quotes_supported": true,
        "quotes_required": false,
        "min_amount": 0,
        "max_amount": 1000000,
        "fields": {
          "type": {
            "description": "methods supported by the anchor for asset deposits",
            "choices": ["SEPA","SWIFT"],
            "optional": false
          }
        }
      },
      "USDC": {
        "enabled": true,
        "quotes_supported": true,
        "quotes_required": false,
        "min_amount": 0,
        "max_amount": 10, 
        "fields": {
          "type": {
            "description": "methods supported by the anchor for asset deposits",
            "choices": ["SEPA","SWIFT"],
            "optional": false
          }
        }
      }
    }
  }

Testing

• ./gradlew test

Documentation

Will update protocol and anchor tests to reflect the change once we reached agreement on the new response format