Add showMosaicButton annotation option

[gremo]

Changelog

### Added
- missing `showMosaicButton` option in the AdminOptions annotation

[kunicmarko20]

Can you check the tests, please?

[gremo]

Sorry, forgot tests, fixed thanks.Sorry, forgot tests, fixed thanks.

[kunicmarko20]

Thank you @gremo

[gremo]

Thanks to you, maybe release 0.2.1? :)

[kunicmarko20]

I thought about doing that after you finish #7? if you are gonna do that

[kunicmarko20]

And it would probably be 0.3.0 😄

[gremo]

Well, I think there is nothing wrong pushing 0.2.1 for the new option, and then release 0.3.0... but it's up to you. By the way, my PR will not break BC, so it could be 0.2.2... do you agree?

[kunicmarko20]

there is no BC for 0.*. But this is more of addition and your new PR also, so that would be 0.3 and then 0.4 release, that is why I wanted to put both into 0.3.0.