feat(project-finance): implement hierarchical task loading and subtasks retrieval

- Enhanced the project finance controller to support hierarchical loading of tasks, allowing for better aggregation of financial data from parent and subtasks.
- Introduced a new endpoint to fetch subtasks along with their financial details, improving the granularity of task management.
- Updated the frontend to handle subtasks, including UI adjustments for displaying subtasks and their associated financial data.
- Added necessary Redux actions and state management for fetching and displaying subtasks in the finance table.
- Improved user experience by providing tooltips and disabling time estimation for tasks with subtasks, ensuring clarity in task management.

worklenz-frontend/public/locales/en/task-drawer/task-drawer.json

@@ -23,6 +23,7 @@
       "show-start-date": "Show Start Date",
       "hours": "Hours",
       "minutes": "Minutes",
+      "time-estimation-disabled-tooltip": "Time estimation is disabled because this task has {{count}} subtasks. The estimation shown is the sum of all subtasks.",
       "progressValue": "Progress Value",
       "progressValueTooltip": "Set the progress percentage (0-100%)",
       "progressValueRequired": "Please enter a progress value",