InsetGraphics: use totalheight for height output

InsetGraphics: use totalheight for height output

Graphics "height" is only the height above the baseline and thus not
what most people will expect. Also, using height can result in a
division by zero with rotation.

Use totalheight now since this means "height of the figure" (independent
of the baseline).

The custom options field can be used if height is really desired.
We handle this in conversion/reversion, respectively, so document
output will not change.

Hence, file format change.

Fixes: #9676