Define a specific dll's Symbol Status in csproj

## Summary
I currently have to re-load Symbols every time I run debug on a sample I am experimenting with. In https://github.com/dotnet/sdk/issues/1458#issuecomment-1270277422 , a feature was added to the SDK to copy debug files from packages: `True` - But this does not actually load the symbols when you start Debugging.

As a suggestion for a feature, Why can't I simply write:

```c#

^^^^^^^^^^^^^^^^^^^^^
```

There may be better ways to do this, but the key idea is that it is a setting in my csproj. This makes sense in that "Just My Code" automatically has symbols loaded for all ProjectReference projects. Having a syntax to force loading symbols for external code would complete the csproj abilities.


## User Impact
This is annoying.