Adds the option to fit the viewport to vertical screenspace (#27061)

Adds the option to fit the viewport to vertical screenspace (#27061)

* Adds the option to fit your viewport to your vertical screenspace

* fixes documentation

* Removes commented-out leftover

* Hides the viewport width slider and also we dont know if the viewport width causing stretching/squishing was a bug present before but we fixed that while we were at it

* Removes commented out leftovers