feat: add tooling for generating text-only packages

[oleksandr-didyk]

Overview

Resolves dotnet/source-build#2655

This PR adds tooling for generating text-only packages. The entrypoint for the tooling is the newly added ./generate-text-packs.sh script, that allows the user to provide a package name, multiple package versions and multiple additional NuGet feeds to restore the package from.

The tooling is a modified version of similar MSBuild logic from dotnet/installer (source)

The tool was also used to re-generate almost all of the currently present text-only packages

Other changes

• renamed ./generate.sh to ./generate-ref-packs.sh to better represent its functionality and not collide with the newly added ./generate-text-packs.sh
• added missing *.csproj files for Microsoft.CodeAnalysis.Collections and Microsoft.NetCore.Platform
• replaced existing LICENSE files with dotnet_library_license (change coming from the NuGet packages themselves)
• updated <licenseUrl> in *.nuspec (change coming from the NuGet packages themselves)

Open questions

• are the license changes valid or should they be reverted?
• is the AllowedTextOnlyExtensions list valid or should be updated / removed completely? Originally copied from dotnet/installer with small additions of the following extensions: .-, .resx, .rtf and .xlf
• existing *.nuspec files differ from those available in the NuGet packages by a few lines specified below. Is this something that should be made part of the tooling or could be added manually by the user?

  <files>
    <file src="*/**" target="/" exclude="obj/**/*.*" />
    <file src="*" target="/" />
  </files>

[omajid]

are the license changes valid or should they be reverted?

If the licenses are actually proprietary, that makes it impossible for open source projects to consume this repo and source-build. What would re-licensing look like?

[MichaelSimons]

Nice discovery!

[oleksandr-didyk]

Update - incorporating PR feedback:

• removed reference to dotnet/installer in target comment
• fixed spacing and formatting in PackageGenerator.proj

[crummel]

are the license changes valid or should they be reverted?

If the licenses are actually proprietary, that makes it impossible for open source projects to consume this repo and source-build. What would re-licensing look like?

I believe Dan S went and got permission to put these under the licenses as currently checked-in so we shouldn't revert. @leecow can probably confirm.

[MichaelSimons]

I believe Dan S went and got permission to put these under the licenses as currently checked-in so we shouldn't revert. @leecow can probably confirm.

I confirmed this with Dan S.

[oleksandr-didyk]

Update - incorporating PR feedback:

• removed changes to package licenses
• unified generator scripts
• extracted ref-pack restore logic and re-used it for text-only packages
• minor improvements to the ./generate.sh script

[oleksandr-didyk]

Update - incorporating PR feedback:

• fixed typos
• fixed formatting

[MichaelSimons]

Changes look nice. I just have a couple comments.

[MichaelSimons]

@oleksandr-didyk, When making changes in response to code review feedback, I find it beneficial to preserve the individual commits. It helps the code reviewers see what was changed versus having to re-review the entire set of changes. The commits can be squashed via GitHub when merging the PR.