[QUIC] Merge Start into Listener constructor

[CarnaViire]

Fixes #2262

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Issue Details

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Fixes #2262

Author:	CarnaViire
Assignees:	-
Labels:	area-System.Net.Quic
Milestone:	-

[ManickaP]

Could we talk about this change first? I'm still not convinced that coupling Start with ctor is a way to go. For example, TcpListener has Start, LocalEndpoint keeps port 0 until you start it. I don't see anything particularly wrong with keeping the behavior same here.