Analyzer doesn't visit Instance of all member references

If the instance is an expression which produces dataflow warnings, this causes the analyzer to miss warnings. The same issue likely exists for all operations which reference an object instance - so references to fields/properties/events/methods. Example:

```csharp
class AccessReturnedInstanceField {
int field;

static AccessReturnedInstanceField GetInstance ([DAM (DAMT.All)] Type unused) => null;

static void TestWrite ()
{
GetInstance (GetUnknownType ()).field = 1; // Should warn for GetUnknownType passed to GetInstance
}
}
```