sentinel dashboard 是否考虑做成类似 `@EnableEurekaServer` 的形式，提供 `@EnableSentinelDashboard`

## Issue Description

*feature request*

### Describe what happened (or what feature you want)

sentinel dashboard 是否考虑做成类似 Spring Cloud Eureka Server 的部署方式，比如

```java
@SpringBootApplication
@EnableSentinelDashboard
public class DashboardApplication {
public static void main(String[] args) {
SpringApplication.run(DashboardApplication.class, args);
}
}

```

然后通过一些配置项来确定规则的改动保存在何种存储中（内存、zookeeper、nacos、redis ...） 这样做可以简化二次配置的难度，也能防止用户在二次改造的时候出现问题

# 预期改造效果如下

## 一、提供一个 starter 并能通过注解开启功能

1. 提供 spring-boot-alibaba-sentinel-dashboard-starter
2. 提供 @EnableSentinelDashboard

启动方式如下：

```java
@SpringBootApplication
@EnableSentinelDashboard
public class DashboardApplication {
public static void main(String[] args) {
SpringApplication.run(DashboardApplication.class, args);
}
}
```

## 二、通过配置可以选择不同的存储方式

```yaml
sentinel:
dashboard:
cluster: false
datasource:
nacos:
namespace: 3c6f4b6a-511a-42cd-b1dd-35e2523216ac
server-addr: nacos.cn:80
group: DEFAULT_GROUP
username: nacos
password: nacos

```

### Describe what you expected to happen

### How to reproduce it (as minimally and precisely as possible)

1.
2.
3.

### Tell us your environment

### Anything else we need to know?

No files, tests, or entry points are named. Start by mapping the Sentinel Dashboard deployment and rule-storage configuration, then use the proposed starter, @EnableSentinelDashboard annotation, and selectable storage backends as the completion criteria.

Written by the indexing model from the issue text.