Merge branch 'master' of http://183.238.195.77:10081/wangjx/sentinel

* Update NacosConfigSender.java
* Update NacosDataSourceDemo.java
* fix(Nacos Demo): remoteAddress error

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

* refactor(dashboard): use AuthConfiguration to manage the bean of auth
* refactor(dashboard): change AuthorizationInterceptor to an interface
* refactor(dashboard): change LoginAuthenticationFilter to an interface
* refactor(dashboard): use AuthProperties to manage auth config
* test(dashboard): use NoAuthConfigurationTest to create no auth configuration for testing

`${user.home}` should be resolve in dashboard runtime, not in maven package goal

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Remove unused code in DefaultBlockExceptionHandler#handle

- The demo was unable to run and stop because of missing namesrv configuration, and now fixed.

Signed-off-by: LIU Ming <hit_oak_tree@126.com>

Signed-off-by: LIU Ming <hit_oak_tree@126.com>

* Add `@Spi` annotation as the general annotation for SPI definition.
* Add isDefault in @Spi, add loadDefaultInstance and improve loadFirstInstanceOrDefault method, improve test cases
* Add SpiLoaderException class for thrown when something goes wrong while loading Provider
* Rearrange packages of base SPI mechanism

NOTE: this PR contains breaking changes regarding API.

* Fix issue of memory leak in metric.js