test: Improve unit test coverage + fix Dubbo global state contamination

[Copilot]

Adds comprehensive unit test coverage across multiple SOFA-RPC modules and fixes a test isolation bug in the Dubbo bootstrap tests where FrameworkModel global state leaked between test classes when Surefire ran them in the same JVM.

New test coverage

• core-impl: RegistryRouter, DirectUrlRouter, Cluster, Filter
• core/api: Exception handling, utility classes
• remoting-bolt: Transport, connection management
• remoting-http: HTTP/2 transport and handlers
• remoting-resteasy: REST adapter, client builder
• codec: Jackson and Fury serializers
• registry: Consul, Mesh, Polaris implementations
• bootstrap: REST, Triple, Dubbo
• tracer: OpenTracing REST and Triple
• fault-hystrix: Circuit breaker integration
• doc-swagger: Swagger generator
• compiler: Triple protocol code generator

Dubbo global state fix

DubboConsumerBootstrapTest and DubboProviderBootstrapTest were initializing Dubbo's FrameworkModel in STRICT mode (the default), leaving ApplicationConfig registrations behind that caused DubboServerTest to fail when run in the same JVM.

Added @BeforeClass/@AfterClass lifecycle hooks to both classes:

@BeforeClass
public static void setUpClass() {
    System.setProperty(ConfigKeys.DUBBO_CONFIG_IGNORE_DUPLICATED_INTERFACE, "true");
    System.setProperty(ConfigKeys.DUBBO_CONFIG_MODE, ConfigMode.IGNORE.name());
}

@AfterClass
public static void tearDownClass() {
    FrameworkModel.defaultModel().destroy(); // releases ports + ApplicationConfig registrations
    System.clearProperty(ConfigKeys.DUBBO_CONFIG_IGNORE_DUPLICATED_INTERFACE);
    System.clearProperty(ConfigKeys.DUBBO_CONFIG_MODE);
}

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