feat(cache): implement hashed API key storage and retrieval

Adds a new hashed key storage mechanism for API keys in the cache. 
Replaces direct mapping to API keys with composite keys based on 
organizationId and name. Implements searching of API keys using 
hash comparisons for improved security. Updates related tests to 
ensure correct functionality and validate the hashing. Also, 
adds support for a new dependency `golang.org/x/crypto`.

graph/converter.go

@@ -38,7 +38,7 @@ func ToGqlAPIKeys(keys []domain.APIKey) []*model.APIKey {
 		result[i] = &model.APIKey{
 			ID:           apiKeyId(k.OrganizationId, k.Name),
 			Name:         k.Name,
-			Key:          &k.Key,
+			Key:          nil, // Never return the hashed key - only return plaintext on creation
 			Organization: nil,
 			Refs:         k.Refs,
 			Read:         k.Read,