Don't blindly set the BuildIpa and CreatePackage values, but instead only set
them (when publishing) if they're not already set.
This makes it possible to publish and not create a package.
Fixes https://github.com/xamarin/xamarin-macios/issues/15696.
* [dotnet] Show an error if an app developer tries to publish a simulator architecture.
* We can't publish a simulator build, so show an error in that case.
* We can't change the default runtime identifier when publishing (to a
publishable runtime identifier), because by the time we know we're
publishing, it's too late to change the runtime identifier. This means that
it'll be required for app developers to specify a runtime identifier when
publishing to a mobile platform, since the current default runtime
identifier is for a simulator build.
Partial fix for https://github.com/xamarin/xamarin-macios/issues/12997.
* Fix typo and improve naming.
* [dotnet] Don't use '_UsingDefaultRuntimeIdentifier', it's already used elsewhere in .NET
* Add support for 'dotnet publish'.
* Add support for a 'PkgPackagePath' for macOS and Mac Catalyst, an MSBuild
property to specify the resulting .pkg path, to reflect the existing
'IpaPackagePath' (for iOS and tvOS).
* Fix MSBuild logic that uses 'IpaPackagePath'. Looks like nobody has ever
used this...
* Add tests.
Fixes https://github.com/xamarin/xamarin-macios/issues/11807.
Rolf Bjarne Kvinge