refactor(parser): Improve Transfer Family models with examples and descriptions

Enhances the Transfer Family parser models with field descriptions and examples using Pydantic's Field() functionality. This improvement provides better documentation and metadata for Transfer Family event parsing, following the pattern established in PR #7100.

All field descriptions are based on official AWS Transfer Family Lambda authorizer documentation and include realistic examples from actual test events.

Closes #7119

Author: dcabib

aws_lambda_powertools/utilities/parser/models/transfer_family.py

@@ -5,8 +5,28 @@
 
 
 class TransferFamilyAuthorizer(BaseModel):
-    username: str
-    password: Optional[str] = None
-    protocol: Literal["SFTP", "FTP", "FTPS"]
-    server_id: str = Field(..., alias="serverId")
-    source_ip: IPvAnyAddress = Field(..., alias="sourceIp")
+    username: str = Field(
+        description="The username of the user attempting to authenticate.",
+        examples=["bobusa", "john.doe", "sftp-user-123", "data-transfer-user"],
+    )
+    password: Optional[str] = Field(
+        default=None,
+        description="The password for authentication.",
+        examples=["mysecretpassword", "Password1234", "secure-pass", None],
+    )
+    protocol: Literal["SFTP", "FTP", "FTPS"] = Field(
+        description="The protocol used for the connection.",
+        examples=["SFTP", "FTPS", "FTP"],
+    )
+    server_id: str = Field(
+        ...,
+        alias="serverId",
+        description="The server ID of the Transfer Family server.",
+        examples=["s-abcd123456", "s-1234567890abcdef0", "s-example123"],
+    )
+    source_ip: IPvAnyAddress = Field(
+        ...,
+        alias="sourceIp",
+        description="The IP address of the client connecting to the Transfer Family server.",
+        examples=["192.168.0.100", "10.0.0.50", "127.0.0.1", "203.0.113.12"],
+    )