Add strings for onion service error pages.

Add onionAuthViewKeys() and onionAuthRemove() Tor controller functions.

Add strings for "Remember this key" checkbox and the new
"Onion Services Authentication" preferences section.

Modify the Tor controller onionAuthAdd() function to remove support
for the nickname parameter (not supported by tor) and add some
missing parameter validation.

The link is now constructed in code (instead of coming from aboutTor.dtd)
and it is:
  https://community.torproject.org/LOCALE
where LOCALE is the current browser locale.

Since #24653 landed securityLevel strings are merged into torbutton.dtd.

Kathleen Brade authored Nov 12, 2019 and Georg Koppen committed Nov 19, 2019

Split the configuration portion of the controller() function into
a new configureControlPortModule() function. This allows the
Torbutton code to continue to own the configuration (with help from
Tor Launcher) while making it possible for the v3 client authentication
prompt to use Torbutton's control port module.

Also, include error information returned by Tor within error objects
generated by the control port module and add support for Tor's new
ONION_CLIENT_AUTH_ADD control port command.