Add zsh tab completion ref test

tests/ref.rs

@@ -35,6 +35,7 @@ ref_tests! {
     tmux_htop,
     vim_large_window_scroll,
     vim_simple_edit,
+    zsh_tab_completion,
 }
 
 fn read_u8<P>(path: P) -> Vec<u8>

tests/ref/zsh_tab_completion/alacritty.recording

@@ -0,0 +1,2 @@
+%                                                                               
 

jwilm@kurast.local ➜  ~/code/alacritty  [?1h=[?2004hccacat cc
+Cargo.lock  Cargo.toml  colors.pl*  copypasta/
cat c

tests/ref/zsh_tab_completion/size.json

@@ -0,0 +1 @@
+{"width":1204.0,"height":676.0,"cell_width":15.0,"cell_height":28.0}