feat: custom netty memory-segment based buffer impl

[derklaro]

Motivation

We're currently using the default memory segment backed buffer implementation provided by netty. While this implementation works, there are still some issues with it. These were resolved in upstream but never published due to the central-portal migration that wasn't done for netty5 yet.

Modification

Add a custom netty buffer implementation that is backed by memory segments with a few modifications:

1. memory segments are allocated manually using malloc and freed using free. This means that we're not using the Arena implementations provided by the jdk (specifically the shared arena), as closing them provides a performance bottleneck due to a required thread handshake to prevent uaf. This can be quite expensive depending on the count of active threads.
2. the bugfixes of the upstream implementation are now already present in our custom implementation. This means that the buffer should now work bug-free.
3. the implementation contains some other cleanups that are now possible after the jdk feature became permanent, e.g. preventing segment slicing when copying segments.

Result

We're using a custom mememory-segment backed buffer implementation that doesn't contain some upstream bugs and is faster to deallocate.

[github-actions]

Test Results

 52 files  +  1   52 suites  +1   2m 51s ⏱️ + 1m 30s
524 tests + 72  524 ✅ + 72  0 💤 ±0  0 ❌ ±0 
889 runs  +106  889 ✅ +106  0 💤 ±0  0 ❌ ±0 

Results for commit cdbcb80. ± Comparison against base commit 5b02c06.

This pull request removes 37 and adds 109 tests. Note that renamed tests count towards both.

eu.cloudnetservice.driver.impl.document.DocumentSerialisationTest ‑ [4] {"b":1,"s":2,"i":3,"l":4,"f":5.0,"d":6.0,"c":"/","string":"Hello, World!","bol":true,"cloud":["Ben?","Yes","No","HoHoHoHo"],"world":{"this":"is","hello":"world","insane":"!"}}, PRETTY
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [14] 2025-06-13
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [23] 08:38:20.273223011
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [28] 08:38:20.273328738Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [29] 08:38:20.273350489Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [30] 08:38:20.273372029+05:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [31] 08:38:20.273388129-03:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [34] 2025-06-13T08:38:20.273512992
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [39] 2025-06-13T08:38:20.273645801Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [4] 2025-06-13T08:38:20.266944953Z
…

eu.cloudnetservice.driver.impl.document.DocumentSerialisationTest ‑ [4] {"b":1,"s":2,"i":3,"l":4,"f":5.0,"d":6.0,"c":"/","string":"Hello, World!","bol":true,"cloud":["Ben?","Yes","No","HoHoHoHo"],"world":{"this":"is","insane":"!","hello":"world"}}, PRETTY
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [14] 2025-06-17
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [23] 10:16:34.297307353
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [28] 10:16:34.297998103Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [29] 10:16:34.298833312Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [30] 10:16:34.299020021+05:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [31] 10:16:34.299284174-03:00
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [34] 2025-06-17T10:16:34.300086492
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [39] 2025-06-17T10:16:34.300732358Z
eu.cloudnetservice.driver.impl.document.gson.JavaTimeSerializerTest ‑ [4] 2025-06-17T10:16:34.285406552Z
…

♻️ This comment has been updated with latest results.