[rack-protection] Consider renaming origin_whitelist to something else

[rhymes]

Following the example of rails/rails#33677 and forem/forem#7147 I'm proposing to take into consideration the replacement of the parameter origin_whitelist in Rack::Protection::HttpOrigin with something else.

Possible alternatives: allow, valid, permitted.

According to a quick search - https://github.com/sinatra/sinatra/search?q=whitelist&unscoped_q=whitelist - in the entire Sinatra code base, that's the only instance.

A possible solution would be to add an alternative parameter and a deprecation notice for the existing one and then remove the latter a couple of releases down the line or something like that.

I can work on the initial PR if agreed.

Thank you!

[jkowens]

@rhymes sounds like a good plan. My initial thought is that permitted is a good replacement. Your help would be greatly appreciated!

[rhymes]

@jkowens thanks for the availability. I sent a PR in #1625 but it failed in most of the builds and I think it's unrelated to the code change but as I'm unfamiliar with sinatra and rack-protection it might be entirely my fault. I tried reading the contributing guide but found nothing that could related.

Could you take a look? Thank you!