Client chosen ICID is not a unique Identifier of server-side logs

[huitema]

Debugging an issue with the interop runner was harder than necessary because a single client connection generated two back to back server connections. Since the qlogs are identified by the ICID, the log of the first connection was overwritten by the log of the second one.

[huitema]

On the other hand, a number of test tools set the ICID to a specific value that identifies the test context. There should be an option to keep using the ICID, even if we switch to using the ICID. There should also be an easy way to retrieve the server initial SCID, maybe from the client's standard output.

[huitema]

Plausible choice is to insert a random number in the file name, or maybe a rendering of the date.

[huitema]

Addressed in PR 1349 -- option to add 16 random bits to the name.