unbound: expand UCI to cover some popular dnsmasq features

Unbound+DHCP (server of your choice) should be able to replicate
a lot of what dnsmasq provides. With this change set Unbound
still works with dnsmasq, but also it can work with a plain
DHCP server. Features have been added within the UCI itself
to act like dnsmasq.

- alone: name each interface relative to router hostname
- alone: prevent upstream leakage of your domain and '.local'
- dnsmasq: use dnsmasq UCI to configure forwarding clauses
- dhcp: work with odhcpd as example of companion DHCP-DNS
- dhcp: convert DHCPv4 leases into EUI64 SLAAC for DNS records
- all: enable encrypted remote unbound-control using splice conf
- all: allow user spliced conf-files for hybrid UCI and manual conf
-- 'unbound_srv.conf' will be spliced into the 'server:' clause
-- 'unbound_ext.conf' will add clauses to the end, example 'forward:'

README HOW TO for dnsmasq-in-serial, dnsmasq-in-parallel, and
unbound-with-odhcpd have better/added UCI starters. HOW TO for
including unbound_srv.conf and unbound_ext.conf are added.
Document new UCI: add_local_fqdn, add_wan_fqdn, dhcp4_slaac6,
dhcp_link, domain, and domain_type

Signed-off-by: Eric Luehrsen <ericluehrsen@hotmail.com>

net/unbound/files/unbound_ext.conf

@@ -0,0 +1,8 @@
+##############################################################################
+# UNBOUND UCI USER ADDED CLAUSES
+#
+# Put your own forward:, view:, stub:, and control: clauses here. This file is
+# appended to the end of UCI auto generated 'unbound.conf'. This is done with
+# include: statement. Notice, it is outside of the server: clause.
+##############################################################################
+