Port infra for regeneration of THIRD-PARTY-NOTICES to runtime repo

[NikolaMilosavljevic]

It doesn't look like I linked to my tooling anywhere--it's over here:
dagood/core-setup@bac3b0d...100d6dc (regen-tpn)

It needs to be ported into https://github.com/dotnet/runtime/tree/master/tools-local/tasks/installer.tasks to be maintainable.

Originally posted by @dagood in #3619 (comment)

[NikolaMilosavljevic]

Infra (target and task) needs to be ported to runtime repo.