add date validation + ignore null rows

[dave-mills]

Extra fixes for import / export

[what-the-diff[bot]]

PR Summary

• Enhanced Date Validation in ProjectRequest.php The 'start_date' and 'end_date' fields now have an improved validation system. This ensures that only valid dates are entered, enhancing the overall data integrity.

• Improvements in Data Handling in ProjectImport.php The 'isEmptyWhen' function now correctly identifies empty rows. It returns 'true' when both 'code' and 'name' fields are null. This improvement helps to accurately classify empty data entries and boost data efficiency.

• Enhancement in Date Format Handling in ProjectImport.php The system can now better handle different 'start_date' and 'end_date' formats (including number formats like integers or floats). It will automatically convert them into 'DateTime' objects. This change can accommodate different date representation styles, reducing errors and improving user flexibility.