CIP Domain Validation: Allow arrays in token metadata

To allow (sub)domains longer than 64 bytes, allow the array of strings
workaround known from other metadata standards.

CIP--HeptaSean-DomainValidation/README.md

@@ -86,14 +86,21 @@ number of DNS):
 | --------------------------- | ------------ |
 | 53                          | DNS Domain   |
 
-The metadatum at this label is a single UTF-8 string – the domain that is
-represented by this token, in JSON representation:
+The metadatum at this label is the domain that is represented by this
+token – either as a single UTF-8 string or as an array of strings, in JSON
+representation:
 ```json
 { "53": "example.org" }
 ```
+or
+```json
+{ "53": [ "very.long.subdomain.for.",
+          "example.org" ] }
+```
 
 Since strings in the metadata of Cardano transactions are restricted to 64
-bytes, this domain is also restricted to 64 bytes.
+bytes, the domain has to be split into such an array of strings if it is
+longer than 64 bytes.
 
 The domain must be a DNS domain name as specified in
 [RFC 1034](https://datatracker.ietf.org/doc/html/rfc1034) and following.

CIP--HeptaSean-DomainValidation/cardano-domain-validation.py

@@ -154,10 +154,20 @@ def query_address(address: str) -> List[str]:
                 asset_info = json.loads(json_body)
                 for asset_object in asset_info:
                     for metadatum in asset_object['minting_tx_metadata']:
-                        if (metadatum['key'] == '53' and
-                                isinstance(metadatum['json'], str) and
-                                is_domain(metadatum['json'])):
-                            result.add(metadatum['json'])
+                        if metadatum['key'] == '53':
+                            if (isinstance(metadatum['json'], str) and
+                                    is_domain(metadatum['json'])):
+                                result.add(metadatum['json'])
+                            elif isinstance(metadatum['json'], list):
+                                domain = ''
+                                for part in metadatum['json']:
+                                    if isinstance(part, str):
+                                        domain += part
+                                    else:
+                                        domain = ''
+                                        break
+                                if domain and is_domain(domain):
+                                    result.add(domain)
     return sorted(result)