Give peers and `exportable` flag, set TRUE when sessions for this peer
should not be exported. This evalualtes if the peer uses confidential
information (like srp username/password), a client certificate OR if the
"ssl_peer_key" contains relative paths.
When SSL is configured with paths for relevant components, like CA trust
anchors, an attempt is made to make this path absolute. When that does
not work or the infrstructure is not available, the peer key is marked
as *local*.
Exporting sessions based on relative paths may lead to confusion when
later imported in another execution context.
Closes#16322
43012cb3af