Support build tags

[metalmatze]

I have the problem of wanting to import a build tool that has a build tag tools.
https://github.com/observatorium/deployments/blob/f460944fe1a95ff062886c95f04a654d3c26910c/Makefile

Not sure how that is supported right now. I'll add it manually and overwrite the build command in the Makefile.

[metalmatze]

I tried adding this to bingo myself and I think it requires a bit more thought.
It seems that all dependencies are written as mod files to disk and then there's essentially no other shared state where we could communicate some additional build tags from the CLI to the generated Makefile. 🤔

[bwplotka]

The only persistency is in .mod file

How I would do is that I would add flag tags to get that has package in it, and I would put -tags (or any other build flags) in comment for direct require.

Bingo uses this already for package path, but we can add build flags on top (e.g tools)

Help wanted. 🤗

[bwplotka]

cc @kakkoyun

[bwplotka]

Another use case: Extended Hugo support: https://github.com/gohugoio/hugo#prerequisite-tools