PowerShell Core has this concept of a build.psm1 file that contains a bunch of functions for building and testing PSCore: https://github.com/PowerShell/PowerShell/blob/master/build.psm1

We should align with those processes so that it's consistent across PowerShell repos.

We can still continue to use InvokeBuild, but we can wrap the Invoke-Build * with the same entrypoints that PSCore has.