feat: add support for DNS-SD via mDNS

[JKRhb]

This PR adds support for discovery via mDNS to the application using espressif's own mDNS component for esp-idf.

As I am working with Xtensa-based ESP32 boards, I have only been able to test this out in my adopted version of this example and not with a RISC-V ESP32, so before merging, it might be best if you try to run it locally first :)

[lu-zero]

We have also deal with rust-lang/cc-rs#1005 ...

[lu-zero]

But it works almost as intended

2024-05-09T12:50:41.806550Z  INFO wot_discovery: ServiceFound("_wot._tcp.local.", "shtc3._wot._tcp.local.")
2024-05-09T12:50:41.806678Z  INFO wot_discovery: ServiceResolved(ServiceInfo { ty_domain: "_wot._tcp.local.", sub_domain: None, fullname: "shtc3._wot._tcp.local.", server: "shtc3-thing.local.", addresses: {192.168.9.193}, port: 80, host_ttl: 120, other_ttl: 4500, priority: 0, weight: 0, txt_properties: TxtProperties { properties: [TxtProperty {key: "scheme", val: Some("http")}, TxtProperty {key: "type", val: Some("Thing")}, TxtProperty {key: "td", val: Some("/.well-known/wot")}] }, addr_auto: false })
2024-05-09T12:50:42.670660Z  WARN list: something went wrong Reqwest(reqwest::Error { kind: Decode, source: Error("duplicate field `@type`", line: 1, column: 470) })

Looks like there is a bug somewhere in wot-td.

[JKRhb]

We have also deal with rust-lang/cc-rs#1005 ...

Oh, the problem reported there actually looks familiar to me 😅

Looks like there is a bug somewhere in wot-td.

Thank you for opening wot-rust/wot-td#2! That PR does seem to solve the issue :)

Do you think we can merge this one already or should we wait until wot-rust/wot-td#2 has landed?

[lu-zero]

It is not related so your change can land now. Then I'll update to use wot-td-0.5.0. :)