packages: support {$pkg}_uninstall events

Emit uninstall events independent of uninstall.fish

docs/en-US/Packages.md

@@ -120,6 +120,7 @@ Inside this hook, you can access two package-related variables:
 Packages can use this hook to clean up custom resources, etc.
 
 > Note: for backwards-compatibility, uninstall hooks will also be run if they are located at `uninstall.fish` in the package root.
+> Hooks may also be triggered by listening for the event `{$package}_uninstall` or `uninstall_$package`.
 
 # Make it public
 

pkg/omf/functions/packages/omf.packages.remove.fish

@@ -17,8 +17,11 @@ function omf.packages.remove -a pkg
 
     # Run uninstall hook first.
     omf.packages.run_hook $path uninstall
-    source $path/uninstall.fish 2> /dev/null;
-      and emit uninstall_$pkg
+    if test -f $path/uninstall.fish
+      source $path/uninstall.fish 2> /dev/null
+    end
+    emit uninstall_$pkg
+    emit {$pkg}_uninstall
 
     if command rm -rf $path
       omf.bundle.remove "package" $pkg