feat: get transport connection stats

[Ma233]

I found that this API provides information similar to chrome://webrtc-internals when attempting to resolve issue #445.
It is particularly helpful when you are not working within the Chrome UI.

Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes/features)
• Docs have been added / updated (for bug fixes / features)

🔵 What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

This PR export get_stats method of RtcPeerConnection to Transport, allowing for easy data manipulation through json serialization.

🟤 What is the current behavior? (You can also link to an open issue here)

Cannot inspect transport stats. Can only get its connection state.

🟢 What is the new behavior (if this is a feature change)?

Can get stats by invoke get_sats method of Transport.

☢️ Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

No breaking change.

ℹ️ Other information

The docs of RTCPeerConnection.get_stats method: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/getStats

Closes #issue

[Ma233]

This PR also adds additional logs for the unstable test_processor_connect_with_did test and removes the stabilization daemon, potentially making it easier to pass.
Even if it failed again, we can look at its stats now 🤣 .

[RyanKung]

COOL