fix iterator equality + add test for proc equality + fix sameType (#21707)

* fix iterator equality + add test also for procs

fixes #21706

* all targets

* and isNil and repr

* separate overloads, fix sameType

* more restricted sameType?

* merge overloads again??

* remove sametype change for now

* fix sameType anyway (CI failure was not related)

---------

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>

tests/typerel/tproctypeclass.nim

@@ -73,4 +73,17 @@ proc main =
   doAssert closureProc is proc
   takesAnyProc(closureProc)
 
+  block: # supposed to test that sameType works 
+    template ensureNotRedefine(Ty): untyped =
+      proc foo[T: Ty](x: T) = discard
+      doAssert not (compiles do:
+        proc bar[T: Ty](x: T) = discard
+        proc bar[T: Ty](x: T) = discard)
+    ensureNotRedefine proc
+    ensureNotRedefine iterator
+    ensureNotRedefine proc {.nimcall.}
+    ensureNotRedefine iterator {.nimcall.}
+    ensureNotRedefine proc {.closure.}
+    ensureNotRedefine iterator {.closure.}
+
 main()