Add build utils to simplify local package sharing

[tmat]

Automatically deletes package built by a project from NuGet cache. This allows build from another repo to use Roslyn package output dir as a package source without manually cleaning up packages for every Roslyn change.

Imports Settings.user.props from Settings.props to allow devs to locally override properties, such as VSSDKTargetPlatformRegRootSuffix.
Adds *.user.props to .gitignore to keep it local.

[tmat]

@genlu @jaredpar ptal

[genlu]

[jjonescz]

Alternative (I think a better one because it works in other repos and maybe more scenarios) is to specify VersionSuffix when packing, I usually do

.\build.cmd -pack /p:VersionSuffix=$(git rev-parse --short HEAD)

That produces a uniquely versioned package.

[tmat]

You'd need to keep updating the version in the other repository with every build though. It also requires building from command line - which is another extra step.

[sharwell]

Burn this with fire. Do not touch my NuGet folder without explicit permission.

Whatever you are trying to do, there are ways to do it. This is not one of those ways.

[tmat]

@sharwell
I don't see why this is a problem. It only affects packages built from Roslyn of the very specific version that you're currently building, i.e. "14.0.0-dev".

[tmat]

Specifically, deleting a package version from the cache doesn't break anything. If a build needs that version it will redownload the package from the sources.
The only way how a locally built dev version of Roslyn package can be in the nuget cache is when you set package source of other local repo to Roslyn packages output dir. Next time this repo builds the cache is repopulated.