ci(jenkins): deploy to AppVeyor when master branch

[v1v]

What

Release to the AppVeyor when build in the master branch.
No more appveyor based

Why

To remove the dependency with the appveyor.

Tests

See here

An example of a dry-run with some echos!

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.Apm.NLog.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.Apm.SerilogEnricher.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.CommonSchema.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.CommonSchema.BenchmarkDotNetExporter.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.CommonSchema.NLog.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

echo dotnet nuget push "C:\Users\jenkins\workspace\gent-dotnet_ecs-dotnet-mbp_PR-53\src\go.elastic.co\apm\ecs-dotnet\build\output\Elastic.CommonSchema.Serilog.1.5.0-ci20200228T170655.nupkg" -k "********" -s "********" 

Artefacts are also stored in Jenkins - see here

[Mpdreamz]

@v1v which feed is this publishing into?

It should go into https://ci.appveyor.com/nuget/ecs-dotnet (can supply an API key for).

The retention on these are limited so best not to share with apm-dotnet-agent

[Mpdreamz]

LGTM, I've disabled the build on appveyor completely as well now as it was falling back on a default MSBuild build without the appveyor.yml file