Additional fuzz targets to improve security testing coverage

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Commit 23c918ee addressed issue #3435 and introduced initial fuzz targets to improve testing coverage. This PR continues that effort by adding more fuzz targets to further increase security testing coverage for Mosquitto.

New broker fuzzers:

• broker_fuzz_bridge_remap_topic_in - Tests bridge topic remapping logic
• broker_fuzz_properties_to_json - Tests MQTT v5 properties to JSON conversion
• broker_fuzz_property_read_all - Tests property reading/parsing
• broker_fuzz_proxy_v1_decode - Tests PROXY protocol v1 decoding
• broker_fuzz_subscribe - Tests subscription handling
• broker_fuzz_will_set - Tests will message setting
• broker_fuzz_ws_prepare_packet - Tests WebSocket packet preparation

New dynamic-security plugin fuzzers:

• dynsec_fuzz_config_from_json - Tests dynamic security config parsing from JSON
• dynsec_fuzz_roles_process_add_acl - Tests role ACL processing

All fuzzers follow the existing fuzzer style in the repository and include seed corpora for effective fuzzing.

Test plan

• Fuzzers build successfully with oss-fuzz infrastructure:

  cd $PATH_TO_OSS_FUZZ
  python3 infra/helper.py build_fuzzers --clean mosquitto $PATH_TO_mosquitto_src
  python3 infra/helper.py check_fuzzers mosquitto

• All fuzzers pass the oss-fuzz check_fuzzers validation
• Seed corpora included for each fuzzer

New broker fuzzers:

• broker_fuzz_bridge_remap_topic_in - Tests bridge topic remapping logic
• broker_fuzz_properties_to_json - Tests MQTT v5 properties to JSON conversion
• broker_fuzz_property_read_all - Tests property reading/parsing
• broker_fuzz_proxy_v1_decode - Tests PROXY protocol v1 decoding
• broker_fuzz_subscribe - Tests subscription handling
• broker_fuzz_will_set - Tests will message setting
• broker_fuzz_ws_prepare_packet - Tests WebSocket packet preparation

New dynamic-security plugin fuzzers:

• dynsec_fuzz_config_from_json - Tests dynamic security config parsing from JSON
• dynsec_fuzz_roles_process_add_acl - Tests role ACL processing

All fuzzers follow the existing fuzzer style in the repository and include seed corpora for effective fuzzing.

Test

• Fuzzers build successfully with oss-fuzz infrastructure:

  cd $PATH_TO_OSS_FUZZ
  python3 infra/helper.py build_fuzzers --clean mosquitto $PATH_TO_mosquitto_src
  python3 infra/helper.py check_fuzzers mosquitto

• All fuzzers pass the oss-fuzz check_fuzzers validation
• Seed corpora included for each fuzzer

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