Add configuration_url and suggested_area for MQTT discovery

**Describe the problem you have/What new integration you would like**

**Please describe your use case for this integration and alternatives you've tried:**

**Additional context**

Please expose the following device properties that can be sent for HA via MQTT discovery message:
-configuration_url (cu)
-suggested_area (sa)

It would be good to be possible to send the device IP address in the configuration_url property so remote access to the web server would be straightforward from HA.

Example for BH1750 actual discovery message with added requested data in bold

{
"dev_cla":"illuminance",
"unit_of_meas":"lx",
"stat_cla":"measurement",
"name":"BH1750 Illuminance",
"stat_t":"bh1750test/sensor/bh1750_illuminance/state",
"avty_t":"bh1750test/status",
"uniq_id":"ESPsensorbh1750_illuminance",
"dev":{
"ids":"c8c9a3f951e0",
"name":"Test light sensor",
"sw":"esphome v2023.10.5 Nov 3 2023, 15:43:59",
**"cu":"http://10.100.11.121",
"sa":"Test area",**
"mdl":"esp32dev",
"mf":"espressif"}}

Start by tracing ESPHome's MQTT discovery message generation and how device properties are serialized. Verify the discovery payload can expose configuration_url and suggested_area, including an IP-based configuration URL, and confirm both values appear in generated messages.

Written by the indexing model from the issue text.