Infer foreign_key when inverse_of is present

[Tiedye]

Motivation / Background

This Pull Request makes the behaviour of has_one and has_many associations more convenient. This new behaviour lines up with what I thought rails did based on the docs, as it is not explicit about if the inverse_of option depends on the foreign_key option.

This makes has_one and has_many associations automatically infer the foreign_key option when the inverse_of option is present.

Detail

When inverse_of is present, rails has all the info it needs to figure out what the foreign_key on the associated model should be. I can't imagine this breaking anything as it doesn't change the default, and anywhere where this would change the inferred foreign_key it would've been broken otherwise I think.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[rafaelfranca]

Can you write a test for this? This code doesn't break any existing test, but nothing prevents this code to be removed in he future, so we need a test to make sure the feature you are adding will not be removed.

Also, this needs a changelog since it is a new feature. It is small, but it is still a feature.

[Tiedye]

@rafaelfranca I updated some of the existing models to use the new behaviour so some various old test now explode when the new behaviour is reverted (test_delete_associate_when_deleting_from_has_many_through_with_nonstandard_id, etc.).

Is that sufficient? It was quick and I figure it is simpler than adding new associations that rely on the new inference, as I am not sure what the conventions are for doing that.

[rafaelfranca]

ha! good idea

[Tiedye]

I'm not sure whats causing the markdown lint failure, the change I made seems to obey the rules the error is complaining about.

[Tiedye]

I'm not sure whats causing the markdown lint failure, the change I made seems to obey the rules the error is complaining about.

Ah, probably just bad timing. #47779

[zzak]

I'm not sure whats causing the markdown lint failure, the change I made seems to obey the rules the error is complaining about.

Whoops, yeah that must have snuck in. Fixed by #47812 if you want to rebase. 🙏 Sorry for the trouble!

[Tiedye]

I think this is good to go, the build failure seems unrelated (the failing test TestCaseTest#test_body_stream was already failing)

[igorkasyanchuk]

misspelling