fix: Enable "encodedInsertableStreams" on browsers supporting it.

[fancycode]

Older versions of Chrome (< 124) required the flag to be passed when creating PeerConnections so "createEncodedStreams" can be used later.

See https://issues.chromium.org/issues/40943169 and https://chromiumdash.appspot.com/commit/ae3454745ca8f623435d658eba7d4bc2dc8aed17

With that also refactored the browser detection of features for E2EE.

The issue happened on one of my machines still on Chrome 122 (was developing on Chrome 132 which doesn't need the flag).