feat: SSRF env var to allow all connections before it's configured

[oetr]

In some projects, network requests can happen after the fuzz test has started, but before the user had a chance to configure allowed/denied connections.

Now the user can start Jazzer with the environmental variable JAZZER_SSRF_PERMISSIVE_UNTIL_CONFIGURED set to a truthy value and all network requests will be allowed, until the user specifies otherwise in the fuzz test using BugDetectors.allowNetworkConnections(...)