Closes #18996
Closes #19090
Closes #19091

* Fix issues with using dogfood compilers

* Replace Restore-Project with Run-MSBuild.

Run-MSBuild sets various properties based on global variables that were not set in Restore-Project.

* Arcade SDK 1.0.0-beta.18613.10

* Keep workaround for bad Test SDK package

* Arcade 1.0.0-beta.18613.19

* Change the order of imports

* Disable SourceLink, Xliff in WPF temp projects

Removes the fixed MSBuild version and moves our floating MSBuild to 15.1
RTM

closes #31479

* Remove RuntimeIdentifier specification

* Arcade directory layout

Previous PR accidentally removed this version.

This version has the capability to detect double writes by the compiler.
Particularly when the XML file from a multi-targeted project is written
to the same location every time.

https://github.com/KirillOsenkov/MSBuildStructuredLog/pull/225

This version can read the branch out of the new structure of the file.

* Use Arcade testing targets

* Skip CodeStyle tests on Mono

* Include net472 in test target frameworks for Mono

* Remove incorrect file existence check.

* Update ADO integration test yaml

This is still needed for running unit tests, but just in one place. We
can remove it everywhere else.

Also replaces some unsafe code with Span<T>.

The project needed an upgrade to netcoreapp2.1 and I deleted
an obsolete workaround by upgrading benchmark.net.

* Use Arcade dotnet install scripts

* Update roslyn-tools build tasks to 1.0.0-beta3.18523.2

* DotNet version check, remove LocateDotNet.

This reverts commit 3e229811.