Add notification system for relay channel state changes

- Introduced a new notification module to handle state change listeners.
- Added functions to register and unregister listeners for relay channel state changes.
- Implemented a queue-based system to manage notifications and listener callbacks.
- Updated core relay channel logic to utilize the new notification system.
- Removed old listener management code from relay channel core.
- Refactored the former listener tests to notify tests and added tests for the notification system, including handling of multiple listeners and queue overflow scenarios.
- Updated CMakeLists.txt to include new source files and headers for the notification module.
- Revised README.md to include warnings about callback execution context and performance considerations.

Refs #1096, #1085 and closes #1097

scripts/run_tests.sh

@@ -10,7 +10,7 @@ if [[ -z "$IDF_PATH" ]]; then
 fi
 
 # ==== 2. Valid Modes and Defaults ====
-valid_test_tags=("core" "tilt" "listener" "all" "relay_chn" "nvs" "run_limit" "batch" "inertia" "direction" "auto" "sensitivity" "counter" "interrupt")
+valid_test_tags=("core" "tilt" "notify" "all" "relay_chn" "nvs" "run_limit" "batch" "inertia" "direction" "auto" "sensitivity" "counter" "interrupt")
 valid_test_profiles=("run_limit" "tilt" "nvs" "nvs_custom" "multi" "full_single" "full_multi")
 arg_tag="all" # Default to 'all' if no tag specified
 arg_profile="full_multi" # Default to 'full_multi' if no profile specified
@@ -24,7 +24,7 @@ print_help() {
     echo "This script builds and runs tests for the relay_chn component using QEMU."
     echo ""
     echo "Arguments:"
-    echo "  -t, --tag [relay_chn|core|tilt|listener|nvs|run_limit|batch|inertia|direction|auto|sensitivity|counter|interrupt|all]  Specify which test tag to run."
+    echo "  -t, --tag [relay_chn|core|tilt|notify|nvs|run_limit|batch|inertia|direction|auto|sensitivity|counter|interrupt|all]  Specify which test tag to run."
     echo ""
     echo "  If no tag is specified, it defaults to 'all'."
     echo ""