vncserver: support Logger debug level

unix/KasmVNC/Logger.pm

@@ -8,9 +8,18 @@ use Data::Dumper;
 sub new {
     my ($class, $args) = @_;
     my $self = bless {
+      level => $args->{level} // "warn"
     }, $class;
 }
 
+sub debug {
+  my $self = shift;
+
+  return unless ($self->{level} eq "debug");
+
+  say { *STDERR } @_;
+}
+
 sub warn {
   my $self = shift;