[ArchStairs] Improve Stairs Creation and ensureBase

Refer to discussion at -
https://github.com/FreeCAD/FreeCAD/pull/18864
https://github.com/FreeCAD/FreeCAD/pull/18651
https://github.com/FreeCAD/FreeCAD/issues/16409

Like Wall, Stairs should do without Base. Base validity tested in execute() prevented the desired and documented behaviour.

With this improvement, EnsureBase() is now only to be run when there is Base. If there is no Base, or Base is not valid, Stairs would be created as declared.

src/Mod/BIM/Arch.py

@@ -832,7 +832,6 @@ def makeStairs(baseobj=None,length=None,width=None,height=None,steps=None,name=N
             stair.Label = label
             ArchStairs._Stairs(stair)
             stairs.append(stair)
-            stairs[0].Label = label
             i = 1
         else:
             i = 0
@@ -841,17 +840,12 @@ def makeStairs(baseobj=None,length=None,width=None,height=None,steps=None,name=N
             stair.Label = label
             ArchStairs._Stairs(stair)
             stairs.append(stair)
-            stairs[i].Label = label
             stairs[i].Base = baseobjI
-
-            if len(baseobjI.Shape.Edges) > 1:
-                stepsI = 1                              #'landing' if 'multi-edges' currently
-            elif steps:
+            if steps:
                 stepsI = steps
             else:
                 stepsI = 20
             setProperty(stairs[i],None,width,height,stepsI)
-
             if i > 1:
                 additions.append(stairs[i])
                 stairs[i].LastSegment = stairs[i-1]