introduce temporary <//> for 'owned' to get this compile with 0.19 (#11145)

* introduce temporary <//> for 'owned' to get this compile with 0.19
* make newTable[string, owned Node]() compile (but it crashes)
* make sink/owned parameters consistent
* make actiontable test compile again
* VM: support sytem.move; makes tests green

lib/system.nim

@@ -1641,6 +1641,9 @@ when defined(nimV2) and not defined(nimscript):
   proc unown*[T](x: T): T {.magic: "Unown", noSideEffect.}
     ## Use the expression ``x`` ignoring its ownership attribute.
 
+  # This is only required to make 0.20 compile with the 0.19 line.
+  template `<//>`*(t: untyped): untyped = owned(t)
+
 else:
   template owned*(t: typeDesc): typedesc = t
   template unown*(x: typed): typed = x
@@ -1662,6 +1665,9 @@ else:
     new(r)
     return r
 
+  # This is only required to make 0.20 compile with the 0.19 line.
+  template `<//>`*(t: untyped): untyped = t
+
 template disarm*(x: typed) =
   ## Useful for ``disarming`` dangling pointers explicitly for the
   ## --newruntime. Regardless of whether --newruntime is used or not