Rename t to tmux-sessionizer

This matches ThePrimeagen's script that mine is based on and that I'll
probably switch to in the future.

I've added to the Nix store as custom-tmux-sessionizer so it doesn't
conflict with the tmux-sessionzer packages that's already in the store.

nix/modules/home-manager/features/cli/zsh.nix

@@ -56,7 +56,7 @@
       zstyle ":completion:*" matcher-list "" "m:{a-zA-Z}={A-Za-z}" "r:|=*" "l:|=* r:|=*"
       autoload -Uz compinit && compinit
 
-      bindkey -s ^f "t\n"
+      bindkey -s ^f "custom-tmux-sessionizer\n"
       bindkey -s ^v "nvim\n"
 
       clear-ls-all() {