add cognitive_complexity lint with limit 10

clippy.toml

@@ -0,0 +1 @@
+cognitive-complexity-threshold = 10

crates/pacdef_core/src/lib.rs

@@ -4,6 +4,7 @@ This library contains all logic that happens in `pacdef` under the hood.
 
 #![warn(
     clippy::as_conversions,
+    clippy::cognitive_complexity,
     clippy::option_if_let_else,
     clippy::redundant_pub_crate,
     clippy::semicolon_if_nothing_returned,

crates/pacdef_macros/src/lib.rs

@@ -3,6 +3,7 @@ Procedural macros for `pacdef`.
 */
 #![warn(
     clippy::as_conversions,
+    clippy::cognitive_complexity,
     clippy::option_if_let_else,
     clippy::redundant_pub_crate,
     clippy::semicolon_if_nothing_returned,