Consider cursor warp when switching workspaces

Fixes a regression introduced in
24a90e5d86.

consider_warp_to_focus has been renamed to seat_consider_warp_to_focus,
moved to seat.c and made public. It is now called when switching
workspaces via `workspace <ws>`.

sway/commands/workspace.c

@@ -157,6 +157,7 @@ struct cmd_results *cmd_workspace(int argc, char **argv) {
 			free(name);
 		}
 		workspace_switch(ws, no_auto_back_and_forth);
+		seat_consider_warp_to_focus(config->handler_context.seat);
 	}
 	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
 }