Add `device_network_id` field to type definition.

[cmsong-shina]

There is warning about Undefined field device_network_id with Lua Diagnostics.
How about add that?

lua_libs-api_v0/st/device.lua

-- Device definition
--- @class st.Device
---
--- A device object contains all of the information we have about a given device that is set to be managed by this
--- driver.  It also provides a number of utility functions that make normal operations for dealing with devices
--- simpler.
---
--- @field public transient_store table ...
--- @field public persistent_store table ...
--- @field public st_store table ...
--- @field public state_cache table ...
--- @field public thread st.thread.Thread ...
--- @field public device_network_id string Unique identifier specific for this device. <------- THIS LINE