[ota-requestor-app] support ESP32

[holbrookt]

Problem

Like the other example apps, ota-requestor-app should be supported on multiple platforms.

This would also be help unblock other ota-requestor-app tasks at the moment, such as #10040 (handling AnnounceOTAProvider cannot be tested on ota-requestor-app on Linux because it begins the OTA process immediately). It also helps unblock #7976, since there are other issues preventing chip-tool from commissioning 2 Linux nodes on the same machine.

Proposed Solution

Add an ESP32 platform implementation for ota-requestor-app which at minimum handles AnnounceOTAProvider