Resolves #50954

Allow for more intuitive specifying of seed node addresses with Nix
syntax.

Seems like you can't have a node as its own seed when it's listening on
an interface instead of an IP. At least the way it was done in the
test doesn't work and I can't figure out any other way than to just
listen on the IP address instead.

Would previously overwrite the binary with the wrapper and thus wrap
itself (resulting in an infinite recursion on execution) for the
binaries in /bin.t

If we have the ability to enable remote JMX we should also support
setting credentials for that because they become required if you turn it
on.

If you're on a multi user system you don't want to have the password in
the nix-store. With the new jmxRolesFile option you can specify your own
protected file instead.

Below that it works but only when supplying a custom password file with
restricted permissions (i.e. outside the nix-store). We can't do that
using an absolute path in the tests.

If the `seedAddresses` is not set, don't force `SimpleSeedProvider` to
be in `seed_provider`. This could cause problems in a multi-datacenter
deployment when a different seed provider is preferred.

Fix Cassandra, improve config and tests