tmux: Use <Esc> to clear selection and cancel

Use <Esc> to clear the selection and cancel copy-mode depending on if
something is selected.

.config/tmux/tmux.conf

@@ -64,6 +64,9 @@ bind-key -T copy-mode-vi v send-keys -X begin-selection
 # Yank into system clipboard
 bind-key -T copy-mode-vi y send-keys -X copy-pipe "xclip -selection clipboard"
 
+# Clear selection or cancel copy-mode when nothing is selected
+bind -T copy-mode-vi Escape if -F "#{selection_present}" { send -X clear-selection } { send -X cancel }
+
 # Navigate panes with <prefix>-[hjkl]
 # NOTE: C-[hjkl] (w/o prefix) moves through vim splits and tmux panes
 #       See vim-tmux-navigator