Translate ToString() over enums

[Danevandy99]

Fixes #33635 and #20604

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[Danevandy99]

@roji @cincuranet This is ready to review again.

[Danevandy99]

@roji GitHub wasn't letting me reply to this comment (https://github.com/dotnet/efcore/pull/33706#discussion_r1623792960), but the behavior we want is for the result to be an empty string if we call ToString on a nullable enum, since that's what C# does (https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1.tostring?view=net-8.0). I tested it, and that change is still necessary, otherwise the code inside that if block bypasses the ToString call and just returns null instead of the empty string.

[Danevandy99]

@roji Of course! Thanks for all your guidance. Is there anything I need to do for this to get it into a release build (I'm assuming it'll be in one of the .NET 9 previews)?

[roji]

Nope, it's merged and will appear in a coming preview!

[Danevandy99]

Awesome, thanks!