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/de_DE/CBeteiligte.json

@@ -12,6 +12,8 @@
     "vmhRumungsklagesBeklagte": "Beklagte",
     "mietinkassosKlaeger": "Mietinkasso (Kläger)",
     "mietinkassosBeklagte": "Mietinkasso (Beklagte)",
+    "kuendigungenVermieter": "Kündigungen (Vermieter)",
+    "kuendigungenMieter": "Kündigungen (Mieter)",
     "adressens": "Adressen",
     "calls1": "Anrufe",
     "contactsBeteiligte": "Freigegebene Nutzer",
@@ -33,6 +35,8 @@
     "vmhRumungsklagesBeklagte": "Beklagte",
     "mietinkassosKlaeger": "Mietinkasso (Kläger)",
     "mietinkassosBeklagte": "Mietinkasso (Beklagte)",
+    "kuendigungenVermieter": "Kündigungen (Vermieter)",
+    "kuendigungenMieter": "Kündigungen (Mieter)",
     "adressens": "Adressen",
     "calls1": "Anrufe",
     "contactsBeteiligte": "Freigegebene Nutzer",