feat: Implement TerminateSelf(string reason) to allow plugins to safely terminate themselves

[ELDment]

Prior to implementing TerminateSelf, plugins could only prevent initialization by throwing exceptions within their Load() override method. Once fully loaded, however, plugins lacked any elegant mechanism for self-termination

So, we implemented a state-aware TerminateSelf method:

• PluginState.Loading: Abort initialization by throwing an exception (handled by outer try-catch)
• PluginState.Loaded: Trigger the standard unload sequence for safe termination while preserving reload capability through css_plugins commands

btw. Rather than injecting the complete PluginContext into BasePlugin (which would enable dangerous control inversion allowing plugins to manipulate framework internals or other plugin instances), we employed interface segregation by introducing ISelfPluginControl. This restricted interface exposes only self-termination capabilities to plugins, 100% adhering to the principle of least privilege and preventing unauthorized access to framework components or cross-plugin manipulation 🤗

[ELDment]

Nothing 😪

[ELDment]

To be honest, I originally tried to recreate SourceMod's SetFailState functionality. However, since CSS has better practices for plugin management, I switched focus to implementing safe unloading instead (rather than putting plugins into a failed state)

Meh, I'm not entirely sure this follows best practices though, so I'd appreciate any thoughts or feedback you might have

[ELDment]

[Need Help] Implementing Silent Execution Termination

I want TerminateSelf to behave like throwing an exception (clears call stack and terminates execution immediately) but without:

• Printing stack traces to console
• Requiring try-catch blocks everywhere

Current Situation:

We're using TerminateWithReason() in our plugins, but it doesn't provide the "immediate termination" behavior we need. The call stack unwinds back to OnTestTerminateCommand, and execution continues normally until the method exits 😅

Desired Behavior:

[ConsoleCommand("Terminate")]
public void OnTestTerminateCommand(CCSPlayerController? player, CommandInfo command)
{
    Console.WriteLine("BEFORE");
    TerminateSelf("TEST");      // Should terminate silently here
    Console.WriteLine("AFTER"); // This should never execute
}

---

To prevent control flow from unwinding back to the original caller, we experimented with throwing an exception after Unload(false);

While this successfully terminates execution due to the absence of exception handlers in the call stack, it results in unhandled exception stack traces being logged to the console, making this approach inelegant and unsuitable for production use

[ELDment]

Nothing 😪

[ELDment]

Well, we successfully solved the Silent Execution Termination problem in commit ba6a8b7

[ELDment]

When TerminateSelf is called within the Load override, we only log the termination reason without stack traces

---

However, when plugins throw unexpected errors during loading (Since this is not intentional on our part), we provide full stack trace details since these are unintentional failures

[ELDment]

Now TerminateSelf still works flawlessly under concurrent programming conditions 🥳

[ELDment]

@roflmuffin
I think we're good to go now, let's do a code review 🤠