Simplify registry data and add a new service data store seperated from registry #2030

[cvictory]

What is the purpose of the change

For issue: #2030

URL works as the carrier for Dubbo internal data transfer at runtime, and is also works as a protocol integrating with the external system: registration center, service query, service management, etc., resulting in serious coupling between the configuration and the registration center, and the data load pushed by the registration center is too large.

Keep URL unchanged at runtime, and even enrich the runtime URL; Keep the immutability of the URL during a single invoke from start to end.
Simplify Registry url as much as possible.
Refactor the way of doing service configuration, rely on Registry currently, switch to third-party Config Center while keeping compatible with old Overrides protocol.
Some data in URL are for service query purpose, we should register this part to another place instead of Registry. And it should be realized as extensible and users can decide to enable it or not.

Brief changelog

• Define a new SPI for store service data. ServiceStore & ServiceStoreFactory
• Remove some parameter from registry . Make it simple. Refer to : [Proposal]Metadata(URL) problems and possible solutions #2030 (comment)
• Implement the SPI with zookeeper as an example.

Verifying this change

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[chickenlj]

Extra new lines here.

[chickenlj]

@cvictory

[diecui1202]

code format

[diecui1202]

LICENSE header.

[diecui1202]

non meaningful comment

[diecui1202]

license info too.

[carryxyh]

Chinese comment

[chickenlj]

• ServiceStore can replace ServiceStoreService as the entrance in RegistryConfig/ServiceConfig.
• Delete useless attributes in ServiceStoreConfig.
• Enrich method signature information, generalized inclusion and realize methods in PojoUtils may help.
• ServiceStore's HA strategy: if the server cannot be reached, ignore and try background. You can reference FailbackRegistry.
• ZK nodes written by ServiceStore should be changed to persistent
• OPS will need to retrieve the ServiceStore instance and I think you should provide the exact URL format used by ServiceStore.
• To decide which keys need to be registered to Registry, we can make it configurable by adding an item in dubbo.properties.
• Add a switch to control the URL registered to Registry: register the complete URL to the registry by default.
• Is it necessary to keep cache files locally in AbstractServiceStore? I think it's too complex, just log the error information in case of write failing can be enough.