smart config generation during `sampo init`

[goulvenclech]

About git.short_tags for PHP (Packagist) project, which are practically mandatory :

I wonder if we can detect this on sampo init and automatically add it to the config?

Originally posted by @rafaeelaudibert in #191 (comment)

In general, init currently generates a useless and outdated configuration. We should probably be able to guess some obvious options from the project... That would be consistent with our North Star: designed to be easy to opt-in and opt-out, with minimal configuration required, sensible defaults