Codechange: [Script] rework how compat-scripts work and are loaded (#13504)

- compat_NNN.nut files now only defines what is needed to downgrade from API NNN + 1 to NNN.
- Automatically load all required compatibility files based on the API version of the script, starting with the latest.

src/ai/ai_instance.cpp

@@ -54,7 +54,7 @@ void AIInstance::RegisterAPI()
 	/* Register all classes */
 	SQAI_RegisterAll(this->engine);
 
-	if (!this->LoadCompatibilityScripts(this->versionAPI, AI_DIR)) this->Died();
+	if (!this->LoadCompatibilityScripts(AI_DIR, AIInfo::ApiVersions)) this->Died();
 }
 
 void AIInstance::Died()