Need to fix symbol and NuGet package publishing

[Aaronontheweb]

Had the following failure during the 2.0.0 release:

dotnet nuget push D:\a\1\s\bin\nuget\Hocon.2.0.0.nupkg --api-key *** --source https://www.nuget.org/api/v2/package
info : Pushing Hocon.2.0.0.nupkg to 'https://www.nuget.org/api/v2/package'...
info :   PUT https://www.nuget.org/api/v2/package/
warn : The <licenseUrl> element is deprecated. Consider using the <license> element instead. Learn more: https://aka.ms/deprecateLicenseUrl.,The <iconUrl> element is deprecated. Consider using the <icon> element instead. https://aka.ms/deprecateIconUrl
info :   Created https://www.nuget.org/api/v2/package/ 496ms
info : Your package was pushed.
dotnet nuget push D:\a\1\s\bin\nuget\Hocon.2.0.0.symbols.nupkg --api-key *** --source https://www.nuget.org/api/v2/package
info : Pushing Hocon.2.0.0.symbols.nupkg to 'https://www.nuget.org/api/v2/package'...
info :   PUT https://www.nuget.org/api/v2/package/
info :   Conflict https://www.nuget.org/api/v2/package/ 275ms
info : To skip already published packages, use the option --skip-duplicate
error: Response status code does not indicate success: 409 (A package with ID 'Hocon' and version '2.0.0' already exists and cannot be modified.).
Running build failed.
Error:
System.Exception: dotnet command failed on nuget push D:\a\1\s\bin\nuget\Hocon.2.0.0.symbols.nupkg --api-key *** --source https://www.nuget.org/api/v2/package
   at [email protected](String message) in C:\code\fake\src\app\FakeLib\DotNetCLIHelper.fs:line 78
   at Fake.DotNetCli.RunCommand(FSharpFunc`2 setCommandParams, String args) in C:\code\fake\src\app\FakeLib\DotNetCLIHelper.fs:line 78
   at [email protected](String project) in D:\a\1\s\build.fsx:line 223
   at Microsoft.FSharp.Collections.SeqModule.Iterate[T](FSharpFunc`2 action, IEnumerable`1 source)
   at [email protected](Unit _arg2) in D:\a\1\s\build.fsx:line 229
   at Fake.TargetHelper.runSingleTarget(TargetTemplate`1 target) in C:\code\fake\src\app\FakeLib\TargetHelper.fs:line 626
Starting FinalTarget: KillCreatedProcesses
Shutting down dotnet build-server
dotnet build-server shutdown
Shutting down MSBuild server...
Shutting down VB/C# compiler server...
MSBuild server shut down successfully.
VB/C# compiler server shut down successfully.

Package format is incorrect and the publishing code isn't robust enough to work around single package failures. Need to fix.