feat(admin-center): implement admin center settings retrieval and enhance holiday population logic

- Added a new API endpoint in AdminCenterController to fetch admin center settings, including organization details.
- Updated the admin center API router to include the new settings route.
- Enhanced the holiday controller to check for recent holiday population before attempting to repopulate, preventing duplicate entries.
- Improved the holiday calendar component to manage holiday population attempts and display loading states.
- Updated localization files to support new messages related to calculation methods and holiday settings.

worklenz-frontend/public/locales/alb/project-view-finance.json

@@ -33,7 +33,7 @@
   "saveButton": "Save",
   "jobTitleColumn": "Job Title",
   "ratePerHourColumn": "Rate per hour",
-  "ratePerManDayColumn": "Rate per man day",
+  "ratePerManDayColumn": "Tarifa për ditë-njeri",
   "calculationMethodText": "Calculation Method",
   "hourlyRatesText": "Hourly Rates",
   "manDaysText": "Man Days",

worklenz-frontend/public/locales/alb/settings/ratecard-settings.json

@@ -48,5 +48,8 @@
   "jobTitleCreatedSuccess": "Titulli i punës u krijua me sukses",
   "jobTitleCreateError": "Dështoi të krijohet titulli i punës",
   "createButton": "Krijo",
-  "cancelButton": "Anulo"
+  "cancelButton": "Anulo",
+  "discardButton": "Hidh poshtë",
+  "manDaysCalculationMessage": "Organizata po përdor llogaritjen e ditëve-njeri ({{hours}}h/ditë). Tarifat më sipër përfaqësojnë tarifa ditore.",
+  "hourlyCalculationMessage": "Organizata po përdor llogaritjen orore. Tarifat më sipër përfaqësojnë tarifa orore."
 }