Upgrade the library to be compatible with MQTTv5 (#343)

## Description

This PR introduces full MQTT v5.0 protocol support to the coreMQTT library. After merging, the library will exclusively support MQTT v5.0 and will no longer be compatible with MQTT v3.1.1.

### Breaking Change

MQTT v3.1.1 support is removed. Users requiring MQTT v3.1.1 should use the last v3-compatible release: [coreMQTT v2.3.1](https://github.com/FreeRTOS/coreMQTT/tree/v2.3.1).

### What's New

- **MQTT v5.0 protocol compliance** — properties, enhanced reason codes, bidirectional DISCONNECT, subscription options
- **Property builder API** — MQTTPropBuilder_t with MQTTPropAdd_* and MQTTPropGet_* functions for all v5.0 properties
- **Enhanced API signatures** — all core functions (MQTT_Connect, MQTT_Publish, MQTT_Subscribe, etc.) now accept optional property parameters
- **Updated event callback** — returns bool and includes reason code and property parameters for bidirectional communication
- **Connection properties** — MQTTConnectionProperties_t tracks server-negotiated values from CONNACK
- **Subscription options** — noLocalOption, retainAsPublishedOption, retainHandlingOption in MQTTSubscribeInfo_t
- **Backward-compatible usage** — all new parameters are optional (pass NULL/0 for v3.1.1-equivalent behavior)

### Migration

See the [Migration Guide](MigrationGuide.md) for API-level changes and the [MQTT v5.0 Guide](MQTTv5Guide.md) for conceptual guidance on using v5.0 features.

### Development History

This PR consolidates all reviewed and tested changes from [PR #343](#343), which contains the full commit history and review discussions. The work 
builds upon the foundation established in [PR #316](#316).

Author: AniruddhaKanhere

.github/.cSpellWords.txt

@@ -28,6 +28,11 @@ misra
 Misra
 MISRA
 MQTT
+mqtteventcallback
+mqttpropadd
+mqttpropertybuilder
+mqttpropget
+MQTTV
 mypy
 nondet
 Nondet
@@ -37,6 +42,7 @@ pytest
 pyyaml
 serializemqttvec
 sinclude
+subscriptionid
 UNACKED
 unpadded
 Unpadded

.github/memory_statistics_config.json

@@ -3,10 +3,14 @@
     "src": [
         "source/core_mqtt.c",
         "source/core_mqtt_state.c",
-        "source/core_mqtt_serializer.c"
+        "source/core_mqtt_serializer.c",
+        "source/core_mqtt_serializer_private.c",
+        "source/core_mqtt_prop_serializer.c",
+        "source/core_mqtt_prop_deserializer.c"
     ],
     "include": [
         "source/include",
+        "source/include/private",
         "source/interface"
     ],
     "compiler_flags": [

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ on:
   push:
     branches: ["**"]
   pull_request:
-    branches: [main]
+    branches: [main, MQTTv5-reviewed-changes]
   workflow_dispatch:
 
 jobs:
@@ -83,6 +83,7 @@ jobs:
         uses: FreeRTOS/CI-CD-Github-Actions/coverage-cop@main
         with:
           coverage-file: ./build/coverage.info
+          branch-coverage-min: 93
 
   complexity:
     runs-on: ubuntu-latest
@@ -92,7 +93,7 @@ jobs:
         uses: FreeRTOS/CI-CD-Github-Actions/complexity@main
         with:
           path: ./
-          horrid_threshold: 12
+          horrid_threshold: 30
 
   doxygen:
     runs-on: ubuntu-latest
@@ -154,6 +155,7 @@ jobs:
           mkdir -p override-include
           cp source/include/stdbool.readme override-include/stdbool.h
           cp source/include/stdint.readme override-include/stdint.h
+          cp source/include/inttypes.readme override-include/inttypes.h
 
           # Build using the custom headers
           cmake -S test -B build/ \