onboarding: Allow first release to be already automated

[radeksimko]

Context

Currently, it is impossible to fully onboard a new product which did not have a release yet.

This is likely mostly because the automation expects a formula to exist before bumping the version in it:

homebrew-tap/util/lambda_trigger/lambda_trigger.go

Line 84 in 2698e7f

formulaURL := fmt.Sprintf("https://raw.githubusercontent.com/hashicorp/homebrew-tap/master/%s/%s.rb", brewType, product)

Proposal

Allow creation of a new formula upon first release.