Add option to run command after inactivity delay (closes #747)

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/config/Config.zig

@@ -57,6 +57,8 @@ hide_borders: bool = false,
 hide_key_hints: bool = false,
 hide_keyboard_locks: bool = false,
 hide_version_string: bool = false,
+inactivity_cmd: ?[]const u8 = null,
+inactivity_delay: u16 = 0,
 initial_info_text: ?[]const u8 = null,
 input_len: u8 = 34,
 lang: []const u8 = "en",