Implement @verticalPosition="auto" for @renderInPlace={{true}}

[mkszepp]

Suppresses #1016.

Until now, @verticalPosition="auto" was not implemented when using @renderInPlace={{true}}. This behavior was expected and documented:

Please note that when rendering the content in place, the vertical position will not automatically detect the best position based on the space around the trigger. You have to explicitly pass verticalPosition="above" to render it over the trigger.

With this PR, verticalPosition="auto" is now fully supported even when @renderInPlace={{true}}.

Special thanks to @velrest, who initially started this work