merge master to release/dev16.4

A recent update to the `ubuntu-16.04` VM image in ADO causes mono/fake to crash and this is blocking all work.  The MacOS version works and follows an identical code path.

Merge master to release/dev16.4

* Consider '_' for members with access modifiers

* Add tests

* Revert

* Add tests with modifiers

Only the 16.3 build uses this file and that branch still has a copy.

replace deprecated nuspec `iconUrl` element with `icon`

Merge remote-tracking branch 'upstream/darc-master-ccc2f9a8-8c49-40d2-a189-a6dc389f609c' into package-icon

* Change cancellation test to not depend on how AwaitTask works

This test is to check that when an Async is started as a Task (via
StartAsTask) that when cancelled the Task isn't immediately marked as
cancelled but instead waits for the underlying Async to finish (normally
via cancellation)

* Add test that AwaitTask ignore async cancellation

Merge master to release/dev16.4

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19476.6

* Add a bind to Parallel test to force async continuations

* Fixing Parallel and more tests

* Use trampoline holder directly

* Split race test to check with and without max degree

* Fix RaceBetweenCancellationAndError tests (use an async that errors)

add build telemetry for Linux/MacOS builds

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19473.5

Merge master to release/dev16.4

Merge master to release/dev16.4

* Eliminate Relax requirement to apply --noframework when referencing mscorlib/system.runtime.dll/netstandard.dll

* Relax requirement to pass --noframework with System.Runtime, netstandard and mscorlib.dll

* Eliminate Relax requirement to apply --noframework when referencing mscorlib/system.runtime.dll/netstandard.dll

* Relax requirement to pass --noframework with System.Runtime, netstandard and mscorlib.dll

Merge release/dev16.3 to master

* Remove the requirement that an explicit FSharp.Core reference requires --noframework

* fsharpqa

* add event every time `#r` is invoked

* pass additional args to script host

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19463.3