Basic `retry` support

https://man.archlinux.org/man/extra/retry/retry.1.en

It'd be nice to have a simple retry command

With the new deno task dependencies, sometimes the parallel dependencies have race-conditions (e.g. they both initialize dependencies at the same time and cause a error, like `error: File exists (os error 17), symlink '../https-proxy-agent@7.0.5/node_modules/https-proxy-agent' -> '/home/runner/work/mizu/mizu/node_modules/.deno/node_modules/https-proxy-agent'`)

Or maybe you want to run a script until some server sends you a particular response, or until a specific file exists (it'd combine nicely with #134)