feat(tmux): add binding for new-window with navigation

For the longest time, I've hade the following binding in my `tmux.conf`:

```tmux
bind c new-window -c "#{pane_current_path}" \; \
  command-prompt -p " Window name:" -I "#{window_name}" "rename-window '%%'"
```

A new window is created, using the same path as my current pane, and I'm
presented with a prompt to give the window a meaningful name, with the default
being 'zsh'. This is great when I need another window for the project I'm
working on, but falls a little short when I want to navigate to a new project.

I frequently use `z` with `fzf` to navigate to
project directories. When opening a window for a separate project, I end up
going through these steps:

- Hit `prefix + c`
- Type the name of the project (to name the window)
- Type `z <project name>` to navigate to the project directory

I want to eliminate the need to type the project name twice and came up with
this mapping:

```tmux
bind z new-window \; command-prompt -p \
  " Window name:" "rename-window '#{?%1,%1,zsh}' \; send-keys z ' %1' C-m"
```

Here, we're reading the project name with `command-prompt`, using the input as
the window name (unless it's blank, in which case we use a format conditional
to substitute 'zsh' as a default name). The input is also used in a send-keys
command to execute `z` when the shell loads, navigating to the project
directory.

shell/tmux/tmux.conf

@@ -94,6 +94,7 @@ set -g renumber-windows on  # renumber windows when a window is closed
 # Prompt to rename window right after it's created
 # set-hook -g after-new-window 'command-prompt -I "#{window_name}" "rename-window '%%'"'
 bind c new-window -c "#{pane_current_path}" \; command-prompt -p " Window name:" -I "#{window_name}" "rename-window '%%'"
+bind z new-window \; command-prompt -p " Window name:" "rename-window '#{?%1,%1,zsh}' \; send-keys z ' %1' C-m"
 
 # set-hook -g after-new-session 'command-prompt -I "#{session_name}" "rename-session '%%'"'
 bind-key C new-session \; command-prompt -p " Session name:" -I "#{session_name}" "rename-session '%%'"