feat: integrate plugins with hooks runner and client registration

- Make hooks property mutable to support plugin hooks
- Add plugin registration logic in static start method
- Create EnvironmentMetadata instances for each client
- Follow Android PR patterns for plugin ordering and registration
- Support multiple client scenarios with respective credentials

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

LaunchDarkly/LaunchDarkly/LDClient.swift

@@ -273,7 +273,7 @@ public class LDClient {
 
     let config: LDConfig
     let service: DarklyServiceProvider
-    let hooks: [Hook]
+    var hooks: [Hook]
     private(set) var context: LDContext
 
     /**
@@ -807,6 +807,26 @@ public class LDClient {
             }
         }
 
+        for (name, mobileKey) in mobileKeys {
+            if let instance = LDClient.instances?[name] {
+                let sdkMetadata = SdkMetadata(name: ReportingConsts.sdkName, version: ReportingConsts.sdkVersion)
+                let environmentMetadata = EnvironmentMetadata(
+                    applicationInfo: instance.environmentReporter.applicationInfo,
+                    sdkMetadata: sdkMetadata,
+                    credential: mobileKey
+                )
+                
+                for plugin in config.plugins {
+                    let pluginHooks = plugin.getHooks(metadata: environmentMetadata)
+                    instance.hooks.append(contentsOf: pluginHooks)
+                }
+                
+                for plugin in config.plugins {
+                    plugin.register(client: instance, metadata: environmentMetadata)
+                }
+            }
+        }
+
         completionCheck()
     }
 
@@ -894,7 +914,7 @@ public class LDClient {
 
     private init(serviceFactory: ClientServiceCreating, configuration: LDConfig, startContext: LDContext?, completion: (() -> Void)? = nil) {
         self.serviceFactory = serviceFactory
-        self.hooks = configuration.hooks
+        self.hooks = Array(configuration.hooks)
         environmentReporter = self.serviceFactory.makeEnvironmentReporter(config: configuration)
         flagCache = self.serviceFactory.makeFeatureFlagCache(mobileKey: configuration.mobileKey, maxCachedContexts: configuration.maxCachedContexts)
         flagStore = self.serviceFactory.makeFlagStore()