fixed localization of doctype naming in overlay content type selector

[frederikreher]

Previously document type names weren't translated as the doctype names were just returned directly from the InnerContentApiController.
I've implemented a basecontroller with a translation method to make sure the naming is correct.

[leekelleher]

Hi @frederikreher, thanks for the PR! (I've been on vacation, hence the delay in my reply).

I'm happy with the doctype name localization being fixed, but I'm not sure why it needs to be in a base class? If you could add the TranslateItem to the InnerContentApiController itself (and make it private/internal), then that'd be great. We could merge it in. Thanks! 😃

[frederikreher]

@leekelleher

I'm not sure what is was thinking at that point, maybe just blindly copying the implementation from core. :-) I've moved the method into the InnerContentApiController now - not sure if you'd like the properties above the methods?

[leekelleher]

Cool, thanks @frederikreher, it's very much appreciated. Merging in now.