API: Add template list endpoint

Fetches all template names that a user has in the templates directory
for chat completions.

Signed-off-by: kingbri <bdashore3@proton.me>

OAI/types/template.py

@@ -0,0 +1,9 @@
+from pydantic import BaseModel, Field
+from typing import List
+
+
+class TemplateList(BaseModel):
+    """Represents a list of templates."""
+
+    object: str = "list"
+    data: List[str] = Field(default_factory=list)