make prepare updates project url and org name

[gpduck]

This extends make prepare with an ORG command line parameter and updates deployment-teplates/.goreleaser.yml and provider/resources.go to use the key abc as a replacement value for the org name. It also updates those files to use the github.com/pulumi/pulumi-xyz repo value where they weren't already and extends make prepare to replace those values with the REPOSITORY configuration variable (instead of relying on the -xyz replacement as before, which did not properly update the repo location for 3rd party repos).

The only manual modifications remaining are to add the proper upstream terraform go module, define the resource mappings, and set various values in provider/resources.go as required (ie download url, image, etc)

This may be sufficient to close #75

[nimro]

Thanks for this, I was having trouble chasing the references down manually. This change helped me get everything working!

[guineveresaenger]

This seems like a solid improvement, and with a testimonial at that. Thank you for your contribution!

Because this pull request is so old (we apologize for the delay!) I've run a rebase for you and requested a review from the team. We can take this change from here.