vim-patch:partial:9.1.0117: Stop split-moving from firing WinNew and WinNewPre autocommands

Problem:  win_splitmove fires WinNewPre and possibly WinNew when moving
          windows, even though no new windows are created.
Solution: don't fire WinNew and WinNewPre when inserting an existing
          window, even if it isn't the current window. Improve the
          accuracy of related documentation. (Sean Dewar)

96cc4aef3d

Partial as WinNewPre has not been ported yet (it currently has problems anyway).

src/nvim/eval.lua

@@ -12699,10 +12699,10 @@ M.funcs = {
     args = { 2, 3 },
     base = 1,
     desc = [=[
-      Move the window {nr} to a new split of the window {target}.
-      This is similar to moving to {target}, creating a new window
-      using |:split| but having the same contents as window {nr}, and
-      then closing {nr}.
+      Temporarily switch to window {target}, then move window {nr}
+      to a new split adjacent to {target}.
+      Unlike commands such as |:split|, no new windows are created
+      (the |window-ID| of window {nr} is unchanged after the move).
 
       Both {nr} and {target} can be window numbers or |window-ID|s.
       Both must be in the current tab page.