New windows don't appear (unless resized by compositor)

New windows sometimes don't get an initial exposeEvent and therefore don't commit anything.

m_widow->applyConfigure sends an expose event for the whole window, the change to call it directly on the shell means we dont' get that.

It sometimes still works as resizeFromApplyConfigure will setGeometry and that'll call expose. However, if the window size is undefined by the compositor then we'll call setGeometry with the size we already have.

There's a fix on review already but Johan said

> create a bug report with P1 and fix version 5.12.0 (i.e. release blocker) so we make sure it gets merged in time?