IoT mcp tools redesign

[ShuxinLin]

in FMSR_revision branch,

the following mcp tools are conflicted:
For list sensors,

AssetOpsBench/src/servers/iot/main.py

Line 233 in 350ec0f

def sensors(site_name: str, asset_id: str) -> Union[SensorsResult, ErrorResult]:

AssetOpsBench/src/servers/iot/main.py

Line 283 in 350ec0f

def asset_sensors(site_name: str, asset_id: str) -> Union[AssetSensorsResult, ErrorResult]:

---

For list assets,

AssetOpsBench/src/servers/iot/main.py

Line 218 in 350ec0f

def assets(site_name: str) -> Union[AssetsResult, ErrorResult]:

AssetOpsBench/src/servers/iot/main.py

Line 303 in 350ec0f

def registry_assets(