Provide machine-readable binary distribution metadata

@maerwald has suggested that it would be useful to have various information about released binary distributions in a machine readable format (e.g. JSON or YAML). Such metadata would include the following for each bindist:

• package versions in bindist package database (addressing #21996)
• operating system the bindist was built on
• gmp, ncurses, libc versions
• perhaps gcc and binutils versions
• build configuration (e.g. flavour)
• ghc --info