Refactor BaseDevice and update Device model structure

- Enhanced the `BaseDevice` class with methods for loading templates and parsing configuration data using TTP.
- Updated the `Device` model to use lists for `interfaces` and `vlans`, allowing for multiple entries.
- Introduced new TTP template files for structured data parsing.

oxi/interfaces/contract.py

@@ -16,10 +16,10 @@ class System(BaseModel):
 
 class Vlans(BaseModel):
     id: int
-    name: str = Field(alias="description")
+    name: str | None = Field(default=None, alias="description")
 
 
 class Device(BaseModel):
     system: System
-    interfaces: Interfaces
-    vlans: Vlans
+    interfaces: list[Interfaces] = []
+    vlans: list[Vlans] = []