Fix MEF issues with options

It seems something changed about MEF import w.r.t. private members.

Author: vzarytovskii

vsintegration/src/FSharp.Editor/Options/EditorOptions.fs

@@ -168,7 +168,7 @@ type EditorOptions() =
     member _.Formatting: FormattingOptions = store.Get()
 
     [<Export(typeof<SettingsStore.ISettingsStore>)>]
-    member private _.SettingsStore = store
+    member _.SettingsStore = store
 
     member _.With value = store.Register value