Currently, make is basically a hard dependency for building the gh binary and its man pages, but make isn't available on Windows. Right now, Windows developers have to run go build with the right arguments manually.

Furthermore, our current Makefile isn't equally portable to all *nix systems. #2578

To expose our build scripts to all platforms equally, I propose we move them to a Go script than could be run like so:

go run script/build.go <task-name>

After that, we can keep a very slim Makefile for backwards compatibility, but all tasks would be delegated to the Go script. That way, only a working version of Go is a prerequisite for developing on GitHub CLI, not any other tools.