refactor: 💡 update credential-library form for password type (#3060)

* refactor: 💡 update credential-library form for password type

* style: 💄 fix display issue

* test: 💍 add test cases

addons/api/addon/generated/models/credential-library.js

@@ -81,9 +81,10 @@ export default class GeneratedCredentialLibraryModel extends BaseModel {
   })
   credential_type;
 
-  @attr('object-as-array', {
+  @attr('object', {
     for: 'vault-generic',
     description: 'It indicates the credential mapping overrides.',
+    emptyObjectIfMissing: true,
   })
   credential_mapping_overrides;
 

addons/api/addon/serializers/credential-library.js

@@ -68,7 +68,9 @@ export default class CredentialLibrarySerializer extends ApplicationSerializer {
    */
   handleCredentialMappingOverrides(serialized, isNew) {
     const { credential_type, credential_mapping_overrides } = serialized;
-
+    if (Object.keys(credential_mapping_overrides).length === 0) {
+      serialized.credential_mapping_overrides = null;
+    }
     // API expects to send null to fields if it is undefined or deleted
     if (credential_mapping_overrides && !isNew) {
       serialized.credential_mapping_overrides = options.mapping_overrides[