Use dotnet-licenses for publishing

[ForNeVeR]

When we publish our compiler bundles and dotnet tool, we publish several dependencies alongside them. These packages have their own licensing policies, and we have to follow them — mainly, list the authors of the packages and their license texts.

Currently, I did a set of hacks and manual actions that provide these and include where appropriate, but eventually I hope that dotnet-licenses will allow to automate it.

Until then, we'll have to perform certain manual actions during release.

See several places in code marked with TODO[#839] and the corresponding actions in the MAINTAINING.md.