Improve Input Validation for Date Handling in getYearsMonthsDaysFromDOB Function

[nidhiisinghh]

Description:
The getYearsMonthsDaysFromDOB function in the OpenELIS codebase currently doesn’t handle date input validation well. It needs improvement to:
1. Ensure that only numeric values are accepted in the expected date format (dd/mm/yyyy or mm/dd/yyyy).
2. Provide better user feedback when the input is empty or invalid.
3. Improve error handling when the input format doesn’t match the required structure.

Current Behavior:
• The function accepts a date in the format dd/mm/yyyy or mm/dd/yyyy but doesn’t restrict input to only numeric characters.
• If the input is in an incorrect format (e.g., "abc/xyz/1234" or an empty string), it logs warnings but doesn’t effectively handle the invalid input.
• There’s minimal feedback to the user regarding invalid input.

Expected Behavior:
• The function should only accept numeric values for the day, month, and year parts of the date.
• It should check the input for the correct format and reject invalid or empty inputs.
• If the format is valid, the function should calculate the difference in years, months, and days between the current date and the provided date.

Steps to Reproduce:
1. Call getYearsMonthsDaysFromDOB with invalid date inputs, such as:
• "abc/xyz/1234"
• ""
2. Observe that while warnings are logged, the function does not handle these inputs properly or provide actionable feedback.

Acceptance Criteria:
• The function should properly validate that the input date contains only numeric characters and follows the format dd/mm/yyyy or mm/dd/yyyy.
• Clear and informative warnings should be logged when the input format is invalid.
• The calculation of years, months, and days should work correctly when valid input is provided.

Priority: Medium

[nidhiisinghh]

I would like to be assigned to this issue.