Initial implemention of a push av server

[fmonniot]

Push AV Server implementation for cameras. This PR is currently a draft to gather early feedback from the camera tiger team. It is not intended to be merged as part of the Matter 1.4 release.

This PR introduce a new tool (src/tools/push_av_server/server.py) that offer a web server to test the PUSH AV Transport cluster. The tool also manage TLS certificates for both the server itself as well as the cameras uploading to it. The server can be interacted with via HTTP calls when used as a standalone tool (work on a UI is in progress) or via python functions when used as a module (mostly targeting the test harness).

Note that test harness integration is mostly a work in progress at this point. The added test file in this PR is only intended as a guide (as well as to provide information onto how the tool can be used in that context) to help develop correct APIs and is not intended to be merged as part of this PR.

The web server provide few checks in term of validation for the ingested media. The idea is to have a server permissive enough that record as much information as possible, and then rely on the actual test to validate that the camera is working as it should.