* Update dependencies from https://github.com/dotnet/arcade build 20200402.9

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.20202.9

* Use custom toolset compiler
Co-authored-by: Ndotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>
Co-authored-by: NAndy Gocke <andy@commentout.net>

Fixes https://github.com/dotnet/metadata-tools/issues/30
Adds support for calli token printing

* Add dotnet-tools feed

* Update PDB Converter to 1.1.0-beta2-20115-01

* Remove symreader-converter myget feed

* Add dotnet5 feed

* Remove symreader, symreader-portable, sourcelink myget feeds

This reverts commit f19214b69c2fbc6aa8431e3aceeb8d805bb99c6f.

This reverts commit 9ef11ce3bcd1ddd60391060962158c2f79215170.

This is the version used in VS 16.5 preview 2 (d16.5 16.5.29721.120)

This restores the compiler toolset from prior to #41575 to mitigate the
build performance regression.

Remove semantic versioning V1 flag as apparently this is not allowed in that format

Change Roslyn to target netcoreapp3.1 when building .NET Core assets.

Previously the code targetted a mix of netcoreapp2.1 and netcoreapp3.0.
The mix is due to default interfaces only being supported on
netcoreapp3.0 and hence our testing needed to use that. Yet at the same
time we were required to ship the compiler in SDKS that targetted
netcoreapp2.1. Now we can universally target netcoreapp3.1.