PM-4669 - support for payment cycles engagement payments

[vas3a]

This pull request enhances the handling of payment details for assignments by introducing support for a paymentCycle field and a standardHoursPerDay field throughout the admin service and related DTOs. These changes ensure that assignment payment cycles and daily standard hours are consistently managed and exposed via the API, improving data accuracy and flexibility.

Payment Details Enhancements:

• Added a new PaymentCycle type ('WEEKLY' | 'FORTNIGHTLY' | 'MONTHLY') and integrated it into the PaymentEngagementDetailsDto and related logic, allowing assignments to specify their payment cycle.

• Introduced a standardHoursPerDay field to PaymentEngagementDetailsDto and related interfaces, with logic to derive its value from standardHoursPerWeek when not explicitly provided.
  Service and Interface Updates:

• Updated AdminService to handle the new paymentCycle and standardHoursPerDay fields when transforming assignment and engagement data, ensuring default values and correct type casting.

• Extended TopcoderAssignmentContext and TopcoderEngagementAssignment interfaces to include the new fields, supporting end-to-end data flow.