Fix unbound shortcut links

[phil-davis]

Fixes redmine #4151

1. Make the naming in shortcuts.inc more clear - forwarder=dnsmasq resolver=unbound
2. Make the value of $shortcuts_section correct in each dnsmasq and unbound php code
3. Make diag_logs_resolver.php smarter, so if dnsmasq is enabled, then show shortcuts for dnsmasq, otherwise show shortcuts for unbound.
4. Fix some references to forwarder in unbound code - should be resolver.

[jim-p]

This all looks good but is there any way you could resubmit this as one single commit, or make a pull request for both master and RELENG_2_2? It's much easier to merge or cherry-pick that way.

[phil-davis]

I do all this stuff online in GitHub. The online editor does not seem to let you save without commit, so I end up with a commit for every file change. I will make a matching pull request for RELENG_2_2 and have at look at using some local Git where I can make edits and then a single commit...

[phil-davis]

Closing in favor of #1405 which will be easier to commit and merge to RELENG_2_2.