Add VLESS seed configurations

[yuhan6665]

@RPRX I think it is ready for review now. I still need to do some test, including compatibility.
I feel this code structure is much better than before. Flexible to implement padding, delay and independent scheduler in the future. Although I don't how to design the user config ;) so currently the config is just on/off and actual values are hard coded and features are basic. But I think the concept should be easy to grasp, e.g:

message Addons {
  string Flow = 1;
  bytes Seed = 2;
  SeedMode Mode = 3;
  string Duration = 4;  // "0-8" means apply to number of packets, "1000b-" means start applying once both side exchange 1kb data, counting two-ways
  PaddingConfig Padding = 5;
  DelayConfig Delay = 6;
  SchedulerConfig Scheduler = 7;
}

enum SeedMode {
  Unknown = 0;
  PaddingOnly = 1;
  PaddingPlusDelay = 2;
  IndependentScheduler = 3;
}

message PaddingConfig {
  uint32 RegularMin = 1;
  uint32 RegularMax = 2;
  uint32 LongMin = 3;
  uint32 LongMax = 4;
}

message DelayConfig {
  bool IsRandom = 1;
  uint32 MinMillis = 2;
  uint32 MaxMillis = 3;
}

message SchedulerConfig {
  uint32 TimeoutMillis = 1; // original traffic will not be sent right away but when scheduler want to send or pending buffer times out
  // Other TBD  
}

[Fangliding]

在掰扯完http的大小写问题之后我们终于见到一些真家伙了

[RPRX]

预计在下个版本中出现，不然下个月现有的 Vision 可能要废了

[RPRX]

先 rebase 一下

[yuhan6665]

先 rebase 一下

done

[RPRX]

虽然本来想赶在下个月前上 Vision seed 但也不会那么快铺开，所以放下个月，以及 VLESS encryption，这个月我们专注 XHTTP

[RPRX]

这个月我们专注 XHTTP

XHTTP 的 XMUX 为我们带来了 h2mux 和 h3mux，且 header 均有 padding 但 body 还没有，所以是时候开搞 Vision Seed 了

[RPRX]

To Nikita Korotaev：我觉得现在就不代理 TLSv1.2 有点早，况且 Vision Seed 一个重要目标就是能配合其它传输层使用如 XHTTP，到时内层 TLSv1.3 也无法裸奔，说起来我更关心的是，听说你们俄罗斯那边下个月要断开国际互联网、IP 白名单？

[iambabyninja]

2RPRX:
Since most European countries are unfriendly toward us and cut us off from international transfers (SWIFT), payment systems (Mastercard/Visa), their services (Microsoft, Google, JetBrains, etc.), and many other corporate services, our country has been conducting annual drills for the banking and financial sector for many years.

The goal of these drills is to understand which areas could be affected by such disconnections and what actions should be taken to minimize the impact of these potential disruptions.

For example, in 2012, during one of these drills, we started considering what would happen if we were cut off from Mastercard/Visa. This led to the development of the “МИР” payment system, and as you know, in 2022, we were indeed disconnected from them.

However, these developments have nothing to do with the work of the censor.
This will not affect regular users. These disconnections only concern the corporate environment and are coordinated with them in advance, taking place once a year.

The latest news about the censor’s work is the blocking of ECH.