Bug - Module `submit_clinical` - extra fields with empty values

[lindaxiang]

Context:

• Part of the metadata has been submitted into the clinical DB
• When metadata submitted through NF workflow contains extra fields with empty values, the module will compare the current metadata is consistent with the committed records in the clinical DB, and verify_registered_data will report an error:
  New field **** detected for existing record... even thought the extra fields have no values.

Solution:
We need to detect whether the metadata to be submitted contains extra fields with real values vs. empty values.