Creation of EveryDueWorkdayMonth

[FMorschel]

Overview

The proposal is to introduce a new class, EveryDueWorkdayMonth, to enhance the capabilities of the package. This class is designed to generate a DateTime that is, for example, the fourth workday of the month, or the 7th, etc.

Related to: #17 and #18

Proposed Class

EveryDueWorkdayMonth
Purpose: This class is designed to generate a DateTime that is, for example, the fourth workday of the month, or the 7th, etc.
Parameters:

• final int dueWorkday - The workday of the month this instance will generate for, inside the month.
  Usage Example:

const secondWorkday = EveryDueWorkdayMonth(2);
secondWorkday.startDate(DateTime(2024)); // would generate `DateTime(2024, 1, 2)`
secondWorkday.startDate(DateTime(2024, 5, 3)) // would generate `DateTime(2024, 6, 4)`

Benefits

Increased Functionality: The addition of EveryDueWorkdayMonth will enhance the package's functionality, catering to specific use cases.

Improved Code Organization: This new class contributes to better code organization by encapsulating the generation of specific workdays within a month.

Usability Enhancement: Users can benefit from EveryDueWorkdayMonth by being able to generate some DateTime that is a certain workday inside the month.

Additional Information

Dependencies: It would extend DateValidatorDueWorkdayMonth, mixin EveryMonth and implement EveryYear and EveryDateValidator.
Testing: It would be needed to test this class similarly to EveryDueDayMonth.

---

Your feedback on this proposal is highly encouraged. I will proceed with the implementation and submit a pull request.