Add initial boilerplate

[saswatamcode]

This PR adds the initial boilerplate for obsctl.

• Adds initial go module for CLI (using kingpin)
• Adds Makefile and bingo for tools and build
• Adds GitHub Actions for CI

[matej-g]

Looking nice 🌹 Not much to add, minus @onprem's comments

[matej-g]

What do you think about grouping all *_metrics.go under this single file, for easier access and readability? Do we need one subcommand per file?

Alternative: Put all in a cmd/metrics/* sub-directory

[saswatamcode]

There might be subcommands of subcommands too. So I just put each logical top-level separate command in a separate file here. 🙂

[matej-g]

Hm then how about the other suggestion with sub-directories? That way we could nicely represent the relationship between parent-children commands.

[saswatamcode]

I looked into this a bit more, about how cobra-based CLIs are organized on other projects (e,g kubectl/skaffold). Let's actually go with the single metrics.go file approach for now! Creating subdirs would require new packages for each top-level command and make sharing stuff like logger much harder.

And instead of having each command as a global variable with init functions to add flags (as suggested by cobra), it'd be better to add functions for each new command and use that (like in other projects). Makes it much more organized! 🙂

[matej-g]

Sounds good, thanks for addressing this!

[saswatamcode]

Have added all the initial commands that we plan for now! Likely this will change a lot once we actually implement the functionality. 🙂

[onprem]

I am not too keen on having global variables, I think we can create wrappers around the Run functions and pass loggers in there.

[onprem]

Just had a small non-blocking comment, but we can tackle that in future PRs. LGTM!