[FEATURE] Implement a DLL injection handshake mechanism.

[Aetopia]

Intent

Currently there is no way to "verify" if a client DLL was injected via our launcher or a 3rd party injector.

Adding some form of verification will provide the following benefits:

• Adds a layer of "guarantee" that the DLL was sourced from the launcher itself.
• Prevents "unwanted" behaviors within the client when injected via a 3rd party injector.
• Provides more control over injection from the launcher's & client's side.

Implementation

A simple handshake implementation can be seen in Stonecutter.

Here:

• The injector uses SetThreadDescription to assign a thread description.
• Once the DLL is injected, it uses GetThreadDescription to obtain the thread description.
• The DLL compares the thread description against an expected thread description.
• The descriptions match then the DLL proceeds to initialize or else fails.