Various support improvements and bugfixes (#2202)

* Organic supports: Added check for variable layer height, with which
Organic supports are not compatible.
Fixes prusa3d/PrusaSlicer#9528 and similar.
Check the object max Z against build volume Z in Print::validate().

Cherry-picked from prusa3d/PrusaSlicer@5b94971

* Fix crash with default tree support

* Show "support_critical_regions_only" only when using auto normal tree supports (#2195)

* Fix organic tree check

---------

Co-authored-by: Vojtech Bubnik <bubnikv@gmail.com>

src/libslic3r/Support/SupportMaterial.cpp

@@ -696,6 +696,9 @@ public:
         case smsTreeSlim:
         case smsTreeStrong:
         case smsTreeHybrid:
+
+        // Orca: use organic as default
+        case smsDefault:
         case smsOrganic:
 //            assert(false);
             [[fallthrough]];