tests: rename test m4 to a nice name

The new m4 also fixes srcdir != builddir issue
tests: Continue button was renamed to 'Next'
tests: initial setup: find windows by roleName


Headerbar is now uses in initial setup wizard, so the name of window changes on moving to a different page
tests: initial setup: rewrite Next/Continue button detection
tests: don't check that Skip Lookup button is hidden due to bug 726539