zsh:keys: Bind ^W to backward-kill-word

For deleting a word while in the shell, I find it easier/faster to use
emacs bindings or Ctrl-Backspace and backward-kill-word instead of the
vi version.

In tmux, Ctrl-H (same esacape sequnce as Ctrl-Backspace) is used for
switching panes since f11b7fa56545 ("vim,tmux:plugs: Add
`vim-tmux-navigator`"), so I need to use Ctrl-W.

As that is bound to vi-backword-kill-word, rebind it to use the emacs
version.

.config/zsh/zshrc.d/60-keys.zsh

@@ -60,6 +60,7 @@ bindkey '^[[P' delete-char                   # delete
 bindkey '^[[3~' delete-char                  # delete
 bindkey '^[[1;5D' backward-word              # ctrl-left
 bindkey '^[[1;5C' forward-word               # ctrl-right
+bindkey '^W' backward-kill-word              # ctrl-W
 bindkey '^H' backward-kill-word              # ctrl-backspace
 bindkey '^[[3;5~' kill-word                  # ctrl-delete
 bindkey "$terminfo[kmous]" kill-word         # ctrl-delete