New 'UserResetAllOptions' hook from the wikiHow codebase.

New 'UserResetAllOptions' hook from the wikiHow codebase.

Location is a tad bit different now than on the wikiHow codebase and some
arguments have been added, as per code review.

Because sometimes you have things that are stored in the user_properties
database table that should *not* be reset even when the user has requested
to reset all prefs back to the site defaults.

Live example of a thing using this hook (well, its previous iteration) is
wikiHow's WikihowPreferences extension.

Change-Id: I1da936c786adb21e2c1802ef405bb904c9cf4918