Resource Explorer creating invalid image resource

_Originally posted by @chipplyman in https://github.com/dotnet/project-system/discussions/9474#discussioncomment-13295770_

Resource Explorer in 17.3.7 creates an icon like so:
```

..\Resources\oracle.ico;System.Drawing.Icon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089

```
This works at first, populating an image in the Neutral Value column. However, on reloading the UI, the Neutral Value column changes to "Failed to load resource value: Type System.Drawing.Icon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 cannot be located."

Managed Resource Editor (legacy) inserts this instead:
```

..\Resources\oracle.ico;System.Drawing.Icon, System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

```
which populates a blank value in the "Neutral Value" column when viewed in Resource Explorer.