The rename functionality relies on deobfuscation for now - so let the user know
this and ask the user to enable deobfuscation to get rename working.

The "Force rewrite deobfuscation map file" option effectively disables
renaming, because renaming relies on deobfuscation map modification for now,
but Force rewrite rewrites the map on each file reload, destroying changes.
So. let the user know this issue instead of silent failure.