PM-6477 manager audit trail

[vas3a]

This pull request introduces a new audit history endpoint for engagement manager assignments and improves timesheet entry visibility and filtering logic, especially for Talent Managers (TMs). It also updates tests to reflect the refined behavior and cleans up related service logic.

Engagement Manager Audit History:

• Added a new GET /audit endpoint to EngagementManagersController that returns the assignment and removal history for engagement managers, using the TimesheetAuditRecordDto. This enables clients to view a detailed management audit trail. [1] [2]
• Implemented the findAudit method in EngagementManagersService to fetch and format relevant audit records, ensuring proper permissions and engagement existence checks. [1] [2]

Timesheet Entry Visibility and Filtering:

• Updated TimesheetsService so that TMs see only submitted entries by default, but can filter for approved entries if specified. This is reflected in both the service logic and the corresponding tests. [1] [2] [3]
• Adjusted filtering logic in timesheet rollup queries to ensure TMs and administrators have appropriate access and filtering capabilities, removing redundant or overly restrictive conditions. [1] [2] [3]