Missing `| null` annotation from tooltip

[MangelMaxime]

Describe the bug

When a type is annotated as T | null I would expect to see | null in the tooltip too.

Steps to reproduce

Create an F# project, with <Nullable>enable</Nullable> set.

type MyEnum2 =
    | Foo = 1
    | Bar = 5
    | Baz = 8

let x: string | null = typedefof<MyEnum>.Namespace

Expected behaviour

Tooltip should display string | null

Screenshots

Code_a8MqhQBh5V.mp4

Machine infos

• Operating system: Windows_NT
• Arch: x64
• VSCode: 1.97.2
• UI Kind: Desktop
• Ionide: 7.25.3
• Runtime: netcore
• Dotnet version: 9.0.103

Additional context

Add any other context about the problem here.

[baronfel]

Yeah - I started on this bug have a blocked PR at ionide/FsAutoComplete#1353. I'd love to get your opinion on it.