add Cloudflare deployer

[xtuc]

Originally reviewed in https://github.com/suborbital/subo/pull/229

[danielledeleo]

Looks like the failed lint is at builder/prereq_test.go:63:9. If you have golangci-lint installed you can run make lint from the project root. It's unfortunate that CI doesn't actually say what failed.

WARN [linters context] gci: `local-prefixes` is deprecated, use `sections` and `prefix(github.com/suborbital)` instead.
builder/prereq_test.go:63:9: err declared but not used (typecheck)
			got, err := tt.prereq.GetCommand(tt.r)

[xtuc]

@jagger27 I can see

but I didn't change that file and err is actually used bellow.

[danielledeleo]

Hi @xtuc, sorry for the delay. Could you try pulling in the latest main? The linter is being a bit aggressive here (we missed it because this specific check is disabled in go1.18).