Add the ability for full installs to optionally use RAM disks for /tmp and /var, and to allow selecting a size for /tmp and /var RAM disks on both Full installs and NanoBSD.
I think I caught most of the edge cases for transitioning into and out of RAM disk mode, and preserving data across reboots as is done on NanoBSD (RRD, DHCP leases, pkg/pbi info).
use logging on the block all v6 rules if default is log
Fix indent and whitespaces
Do not route do default gw when rule gw is down

- Add a new advanced misc option to change the behaviour
- When it is set and rule has its own gateway, that is down, just
  disable the rule instead of routing it to default gw

Fixes #2858