- aspnet/AspNetCore-Internal#1735
- port aspnet/Extensions@e2bb8ac1a0 fix into this repo
- change `default-build.yml` instead of `azure-pipelines.yml`
- make a couple of changes to `KillProcesses.ps1` (which I'll take back to Extensions)
- remove `ci-official.yml`
Part of #4246
Changes:
* Update source code layout to follow the new conventions for this repo
* Update project files to use `<Reference>`
* Update targets to build NPM packages
* Update BuildTools to support custom 'restore' and 'test' targets