Remove unparse and restore aliases.

[casperisfine]

These were deprecated 16 years ago.

[Earlopain]

Hm, should this have been done in a patch version? From the comment the intention was to deprecate, but it hasn't actually happened (only nodoc). It breaks sidekiq-batch because it uses JSON.unparse here.

A fix is simple enough but there was no deprecation warning for this alias that would have helped me out here.

[casperisfine]

but it hasn't actually happened (only nodoc).

nodoc means it isn't public API hence can be removed, so it was effectively deprecated. I get that an actual deprecation warning would have been better.

That being said, since I never saw unparse used in the past I assumed it was just some left over, a quick code search shows there is indeed some use in the wild: https://github.com/search?q=JSON.unparse+language%3ARuby&type=code&l=Ruby.

So perhaps it should go through explicit deprecation.

[Earlopain]

I would say nodoc implies that is was documented at some point (although I haven't been around Ruby 16 years ago, so I wouldn't know personally). Looks like for sidekiq-batch, it was only added 8 years ago with breamware/sidekiq-batch@7792062. Can't really tell why that was done though 🤷