Visual Studio should show a question mark on optional members in completion lists and quick info

[DanielRosenwasser]

We currently give false confidence of the presence of a property, and this is probably a source of many bugs.

• Show a ? at the end of the name in a completion item and in quick info.
• Use a different icon.

[mhegazy]

We need to identify the way this is going to be presented. if it is merely a "?" at the end of the name, that can be added to getCompletionsAtPosition. if we would like to show this with a different icon, which I personally prefer, you will need to first change the CompletionEntry, and CompletionEntrydetails to include an isOptional field, or add a new optional modifier to the list in ScriptElementKindModifier.

[DanielRosenwasser]

According to @CyrusNajmabadi adding an icon would be difficult. I created two checkmarked items to track both halves.

[DanielRosenwasser]

Also this should be shown in quickinfo as well