Tooling does not offer to open namespace for attributes applied to method arguments of interfaces..

**Is your feature request related to a problem? Please describe.**
I expect tooling to work consistently, but VS does not offer to open `System.Runtime.InteropServices` namespace for `[]` and `[]` attributes applied to method arguments.

This is actually not only about theses attributes, but a general issue.

```FSharp
module Bar =
[]
type MyAttribute() = inherit Attribute()

type IFoo =
abstract bar: [] value: string -> string

type Foo() =
member this.Bar([] value:string) = value
```
VS offers to open module for `My` in `Foo`, but fails to do so for `IFoo`