Rewrite stories to CSF3 format

[certainlyakey]

Summary

In Storybook 7.0 the new default stories format is CSF3. In preparation for upgrading to that version we could rewrite all the stories in CSF3 format because it is already supported at least starting from 6.4.

This could help with the whole effort of upgrading to 7.0 somewhere in future.

What alternatives have you tried?

No response

Does this feature request involve any updates to the reference design?

No

Implementation details

We could also use this trick to decrease amount of custom templates provided to stories and instead rely on automatic template generation by Storybook itself, while keeping the advantage of being able to play with projected content as a Storybook control. The trick would apparently work with CSF2 format too.