vim-patch:9.1.0059: No event triggered before creating a window

Problem:  No event is triggered before creating a window.
          (Sergey Vlasov)
Solution: Add the WinNewPre event (Sergey Vlasov)

fixes: vim/vim#10635
closes: vim/vim#12761

1f47db75fd

Not sure if this should be triggered before creating a floating window,
as its use case is related to window layout.

Co-authored-by: Sergey Vlasov <sergey@vlasov.me>

runtime/lua/vim/_meta/api_keysets.lua

@@ -218,6 +218,7 @@ error('Cannot require a meta file')
 --- |'WinEnter'
 --- |'WinLeave'
 --- |'WinNew'
+--- |'WinNewPre'
 --- |'WinResized'
 --- |'WinScrolled'