Audio offset is integer based in configuration, so let's make sure not
to show that there's an applicable offset when the value difference is
too low.
I've also fixed rounding to match expectations (`AudioOffset` is
precision limited to integer), and handled the case where a user adjusts
the slider but also has a suggested offset – previously it would not
enable the button after slider adjustments but now it will work as
expected.
Apparently useful in modding workflows when you want to test out a few
different variants of a thing.
Re-uses `Ctrl-L` binding from stable. Some folks may argue that the
dialog makes the hotkey pointless, but I really do want to protect
users from accidental data loss, and also if you want to power through
it quickly, you can hit the 1 key when the dialog shows, which will
bypass the hold-to-activate period (which wasn't intentional, but so
many people want a bypass at this point that we're probably keeping that
behaviour for power users).