feat: Add termination functionality for rental agreements

- Introduced new entity `CKuendigung` for managing terminations.
- Added fields for termination details including date, reason, type, and status.
- Implemented backend service to initiate terminations from rental agreements.
- Created frontend handler for termination actions with confirmation dialog.
- Updated metadata and layouts for `CKuendigung` to support new functionality.
- Added internationalization support for English and German languages.
- Enhanced existing entities to establish relationships with terminations.

custom/Espo/Custom/Resources/i18n/en_US/CBeteiligte.json

@@ -11,6 +11,8 @@
         "vmhRumungsklagesKlaeger": "Plaintiff",
         "mietinkassosKlaeger": "Rent Collection (Plaintiff)",
         "mietinkassosBeklagte": "Rent Collection (Defendant)",
+        "kuendigungenVermieter": "Terminations (Landlord)",
+        "kuendigungenMieter": "Terminations (Tenant)",
         "contactsBeteiligte": "Portal Users",
         "dokumentesBeteiligte": "Documents"
     },
@@ -27,6 +29,8 @@
         "vmhRumungsklagesKlaeger": "Plaintiff",
         "mietinkassosKlaeger": "Rent Collection (Plaintiff)",
         "mietinkassosBeklagte": "Rent Collection (Defendant)",
+        "kuendigungenVermieter": "Terminations (Landlord)",
+        "kuendigungenMieter": "Terminations (Tenant)",
         "contactsBeteiligte": "Portal Users",
         "dokumentesBeteiligte": "Documents",
         "bankverbindungens": "Bank Accounts"