Analytics: SelectItem inconsistency in types

[jeffreydelooff]

In this PR the description was used to remove the content_type but wasn't actually removed from the types itself. The official docs does not have a content_type field either.

I have tested sending an event with and without the content_type field and luckily Firebase didn't give any errors. From previous testing with standard events I have had errors in the past when using "unsupported"/custom field names.

Is it worth it to make a PR for this to avoid confusion?

[mikehardy]

Hey @jeffreydelooff 👋 - that looks spot on as a change + potential PR, would be happy to merge it - I fear since it is removing a type it's a breaking change for many, so it might queue for a little bit waiting for a v16. Perhaps 2 PRs, one with a @deprecation the second with the removal ?