Add fuzzer for RedisDecoder

[yawkat]

Parent: #231

Add a fuzz target for io.netty.handler.codec.redis.RedisDecoder.

Scope:

• Create fuzzing-tests/src/main/java/io/netty/handler/codec/redis/RedisDecoderFuzzer.java.
• Mirror the Netty target package: io.netty.handler.codec.redis.
• Upstream Netty source: netty/netty:codec-redis/src/main/java/io/netty/handler/codec/redis/RedisDecoder.java.
• Suggested input surface: RESP byte streams covering simple strings, errors, integers, bulk strings, arrays, inline commands, and partial input.
• Follow existing handler fuzzer conventions: @FuzzTarget, fuzzerTestOneInput(...), and main(...) using LocalJazzerRunner.

Rationale:
Parses Redis RESP bytes with an explicit decode state machine and length handling.

Acceptance criteria:

• The fuzzer builds and runs locally.
• Expected Netty validation/decoder/encoder exceptions are handled consistently with existing fuzzers.
• The new fuzzer is included in the fuzzing test targets.