Modifying settings on an already started connection can lead to aborting the connection

[guhetier]

For instance:

• create a connection
• start the connection
  • the "default stream receive window" is sent to the peer as part of the transport parameters
• change the settings, and set a smaller "stream receive window default"
• the peer creates a stream and send data
  • the peer uses the initial stream receive window (from the transport parameter)
• the local connection receives more data than allowed by the newly set stream receive window
• the local connection aborts with "transport error"

Changing settings should fail when modifying a setting that cannot be honored after the connection start (either because it goes in the transport parameters or because it requires a change that cannot be done on a started connection)

[guhetier]

Issue found from discussion on #5690 about assertion validity.