[JIRAALIGN-2886] Import : FeatureHeaderRow error due to missing Header & ColumnNames in XML

Issue Summary

AjaxObjectsImport.asp is throwing "Object required: 'FeatureHeaderRow'" error due to missing Header and ColumnNames in XML

• It fails silently and does not warn the user on import file inconsistency.
• UI just shows "0 (zero) work items to add" as if there were no items to upload.

Steps to Reproduce

1. Download ImportObjectsTemplate.xls
2. Add work items as necessary
3. Save the file

Expected Results

• If Header and ColumnNames parameters are missing, a warning should be displayed to the user informing about the malformed header in the input file.
• To be confirmed by PdM

Actual Results

• It fails silently and does not warn the user on import file inconsistency.
• UI just shows "0 (zero) work items to add" as if there were no items to upload.
• FeatureHeaderRow error is thrown in the background:

  { [-]
     ASP_function: Error.asp
     ErrorId: 13641
     PageName: Import
     correlationid: 57h6Z8+ngD6ig9pUQKEqPhW6LZ1RzHMjFxqLbCow2MA=
     customer_db: instance
     error_aspcode:
     error_aspdescription:
     error_category: Microsoft VBScript runtime 
     error_column: -1
     error_description: Object required: 'FeatureHeaderRow(...)'
     error_file: /AjaxFiles/AjaxObjectsImport.asp
     error_line: 1507
     error_number: -2146827864
     error_source:
     log_type: exception
     logfrom_location: Website-ASP
     timestamp: 2021-02-23T11:16:24.871000-05:00
     url: https://instance.jiraalign.com:443/AjaxFiles/AjaxObjectsImport.asp?Type=5&FileName=Import_Template.xml
     urlverb: POST
     user: 1988
     version: 10.87.0.14952
  }

Workaround

• Ensure import file contains Header and ColumnNames parameters on its headers by saving it as an Excel 2004 XML Spreadsheet file type.