Update unbound_manager.sh

Fix: Demise of jackyaz hosting repository - Thanks SNB Forum member @fourty6and2 
Fix: Don't scan '/tmp/menutree.js' if it doesn't exist
New: Add command 'localhost { domain_name {IP_address | 'del'} } ' to create entries in '/opt/share/configs/unbound.conf.add.localhosts'
     and menu description "localhost = Add { domain_name {IP_address | 'del'} }"
Change: Debug commandline option
Change: Only perform 'unbound-checkconf' against 'unbound.conf' files when Start/Restart (command 'rs') requested. 
        (Eliminates annoying pause when drawing status menu screen (especially if a large Adblock file is configured)
Change: 'unbound-checkconf' now detects non-Fatal syntax errors when checking unbound configuration files (e.g. Adblock 'local-zones:'), so display them.
Fix: Enforce mandatory filename argument to command 'el {Ad Block file}' - Thanks SNB Forum member @francovilar
Fix: Command 'vb [filename]' to reinstate that the 'filename' is optional, and update the menu description. - Thanks Thanks SNB Forum member @make WiFi Great Again
Fix: Correct the menu option 
             "v = View ('/opt/var/lib/unbound ' unbound.conf)" 
             to
             "v = View ('/opt/var/lib/unbound/unbound.conf')" - Thanks SNB Forum member  @Peterr
Change: If 'jitterentropy-rngd' installed in RMerlin firmware, then the 'haveged' package is redundant and should not be installed and removed if found.
Fix: If ALL traffic is forced via VPN then correct the extraction of the VPN tunnel IP - Thanks Thanks SNB Forum member @AlexanderPavlenko)
Change: Expose 'Advanced' menu option 'rs' for 'Easy' menu
Fix: Suppress IPv6 messages issued by unbound-anchor if IPv6 is not ENABLED - Thanks SNB Forum member @Ubimo
              [1635840436] libunbound[16108:0] error: udp connect failed: Cannot assign requested address for 2001:dc3::35 port 53
              [1635840436] libunbound[16108:0] error: udp connect failed: Cannot assign requested address for 2001:503:c27::2:30 port 53
Fix: Cache metrics report after using 'rs' command was meaningless, so postpone extracting them - Thanks Thanks SNB Forum member @Ubimo
              11:51:43 Saving unbound cache to '/opt/share/unbound/configs/cache.txt' msg.cache=5110/4640 rrset.cache=8250/7570
              11:51:47 Restoring unbound cache from '/opt/share/unbound/configs/cache.txt' (2021-11-28 11:51:43) msg.cache=0/4640 rrset.cache=0/7570
			           should be no-zero e.g.
			  11:51:47 Restoring unbound cache from '/opt/share/unbound/configs/cache.txt' (2021-11-28 11:51:43) msg.cache=xxxx/4640 rrset.cache=xxxx/7570

FIX: Explicity reference Busybox version of '/bin/uname' as Entware version (if coreutils-uname installed) now reports different output - Thanks SNB Forums member @htmlspinnr
FIX: RT-AX6000; test for Enware installed using '[ -f "/opt/bin/opkg" ] replaced by [ -n "$(which opkg)" ]
New: Add commandline option 'stop'