Fix analyzer, docs file packaging and don't overbuild runtime.native IO.Ports packages.

[ViktorHofer]

This commit fixes analyzers which were dropped from the package during
the clean-up of pkgprojs and missing documentation files.

1. Analyzers were dropped from the package because the BeforePack
   hook wasn't respected. This happens when the NuGet Pack nuget package
   is referenced which then gets imported before the packaging.targets
   file. The BeforePack property needs to be set in a props file if
   NuGet's targets file isn't used from the SDK but from its package.
2. Documentation files were dropped as the
   DefaultAllowedOutputExtensionsInPackageBuildOutputFolder property
   didn't include the .xml extension.
3. runtime.native.System.IO.Ports.csproj is referenced both in the src.proj
   traversal project and in System.IO.Ports.csproj. The latter reference is
   necessary in order to make it appear as a dependency in the
   System.IO.Ports nuget package. The ProjectReference was missing the
   BuildReferences=false attribute and hence the
   runtime.native.System.IO.Ports project was built twice which resulted
   in multiple concurrent builds likely with different global properties.

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Issue Details

---

This commit fixes analyzers which were dropped from the package during
the clean-up of pkgprojs and missing documentation files.

1. Analyzers were dropped from the package because the BeforePack
   hook wasn't respected. This happens when the NuGet Pack nuget package
   is referenced which then gets imported before the packaging.targets
   file. The BeforePack property needs to be set in a props file if
   NuGet's targets file isn't used from the SDK but from its package.
2. Documentation files were dropped as the
   DefaultAllowedOutputExtensionsInPackageBuildOutputFolder property
   didn't include the .xml extension.

Author:	ViktorHofer
Assignees:	ViktorHofer
Labels:	area-Infrastructure-libraries
Milestone:	-

[ViktorHofer]

Failures are:

• FileStream_WriteAsync_AsyncWrites.WriteAsyncCancelledFile test failed #56894
• Test failure: SimpleScenario_UseGETVerb_Success #57123

[ViktorHofer]

@dotnet/dnceng @ilyas1974 do we have an issue open for super slow machines running on CI? CoreCLR Product Build OSX x64 checked took 2 hours to just build half of the runtime and then timed out (2 hour cap on the leg).

https://dev.azure.com/dnceng/public/_build/results?buildId=1285173&view=logs&jobId=1f8f000c-1adc-5434-677a-95dd9e006aba&j=1f8f000c-1adc-5434-677a-95dd9e006aba&t=2945a4f3-4f84-5b54-c962-533fbace1ff1

[jakubstilec]

@ViktorHofer there is no open issue for this. This is an issue on AzDO Mac OS pool, not on helix queues. Checking.

[jakubstilec]

I retried and the failed job and it finished in 36 minutes. It looks like only temporary issue with one MacOS node. In a case this happens again, affected node was:

Agent name: 'Azure Pipelines 9'
Agent machine name: 'Mac-1628587082288'

[ViktorHofer]

It depends on the machine being used in the pool. We have been seeing this multiple times over the last months. It might make sense to go through the build data to see how often this is happening?

[jakubstilec]

I created a work item for it https://github.com/dotnet/core-eng/issues/14027

[safern]

LGTM