dashboard 持久化扩展

[fengjx]

Describe what this PR does / why we need it

1. dashboard 规则配置保存在内存中，重启后丢失数据，无法在生产环境使用
2. metrics 数据保存在内存中，无法支持高可用，重启后也会丢失数据

Does this pull request fix one issue?

• #1759
• #2179
• #3035

Describe how you did it

• DynamicRulePublisher和DynamicRuleProvider接口增加 apollo 持久化实现
• MetricsRepository 接口增加 redis 持久化实现

Describe how to verify it

see: https://github.com/fengjx/sentinel-dashboard-demo

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