feature: Support metadata-based registration and discovery in Seata

[YoWuwuuuw]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

This PR is used to provide metadata service registration and discovery capabilities for Seata, and supports the registration type of NamingServer.

Ⅱ. Does this pull request fix one issue?

fixes #7532

Ⅲ. Why don't you add test cases (unit test/integration test)?

• Unit Test: All affected modules have passed updated unit tests

  • Because the namingserver module lacks integration testing methods, and the test methods are annotated with @Disable, added mock test for NamingseverRegistryServiceImpl class

• Integration Tests:

  • Server: Metadata defined in the configuration is successfully uploaded to the namingserver.
  • Namingserver: Metadata is correctly persisted and queryable.
  • Client: Metadata is successfully fetched via NamingServerRegistryServiceImpl and parsed into ServiceInstance.

Ⅳ. Describe how to verify it

Simple Test

Server-side config metadata and choose namingserver as the registration center:

Able to lookup the corresponding metadata information, which is included in the ServiceInstance list:

Demo

Pull the https://github.com/YoWuwuuuw/incubator-seata/tree/gsoc-metadata-support branch locally, package the latest code, execute clean install -DskipTests, pull https://github.com/YoWuwuuuw/dubbo-samples-seata and load the Maven dependency, and import the new version code of install.
Start a namingserver, get the generated password and modify the client configuration. Start two servers(new code), use namingserver as the registration center, set registry.metadata.weight=100 for server1 and registry.metadata.weight=1 for server2.
Start the demo according to the demo's readme. Because the configured load balancing policy is WeightedRandomLoadBalance, server 1 has a load probability exceeding 99% after weight calculation. Therefore, the client will connect to server 1 for every request. Then, if server 1 is stopped, the client will reconnect to server 2, proving that the metadata is valid in the load balancing link.

Ⅴ. Special notes for reviews

Other:

• Added UT for FileRegistryService and FileRegistryProvider.
• Removed unused methods, configuration entries and test cases(e.g., redundant registry.conf entries).
• Refactored code for improved readability.
• Added Java doc for affected classes and methods.

[codecov]

Codecov Report

Attention: Patch coverage is 52.09581% with 160 lines in your changes missing coverage. Please review.

Project coverage is 60.52%. Comparing base (f226c66) to head (1c9385d).

Files with missing lines	Patch %	Lines
.../namingserver/NamingserverRegistryServiceImpl.java	35.00%	38 Missing and 1 partial ⚠️
...scovery/registry/raft/RaftRegistryServiceImpl.java	7.69%	24 Missing ⚠️
...overy/registry/nacos/NacosRegistryServiceImpl.java	4.16%	23 Missing ⚠️
...scovery/loadbalance/WeightedRandomLoadBalance.java	62.50%	8 Missing and 10 partials ⚠️
...scovery/registry/sofa/SofaRegistryServiceImpl.java	0.00%	11 Missing ⚠️
...overy/registry/redis/RedisRegistryServiceImpl.java	62.50%	4 Missing and 2 partials ⚠️
.../apache/seata/common/metadata/ServiceInstance.java	88.63%	0 Missing and 5 partials ⚠️
...ta/core/rpc/netty/AbstractNettyRemotingClient.java	0.00%	5 Missing ⚠️
...eata/core/rpc/netty/NettyClientChannelManager.java	50.00%	4 Missing and 1 partial ⚠️
...che/seata/core/rpc/netty/NettyServerBootstrap.java	50.00%	5 Missing ⚠️
... and 6 more

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #7533      +/-   ##
============================================
+ Coverage     60.50%   60.52%   +0.01%     
  Complexity      658      658              
============================================
  Files          1298     1300       +2     
  Lines         49081    49196     +115     
  Branches       5771     5791      +20     
============================================
+ Hits          29697    29775      +78     
- Misses        16750    16777      +27     
- Partials       2634     2644      +10     

Files with missing lines	Coverage Δ
...scovery/loadbalance/ConsistentHashLoadBalance.java	84.61% <100.00%> (ø)
.../discovery/loadbalance/LeastActiveLoadBalance.java	100.00% <100.00%> (ø)
...eata/discovery/loadbalance/LoadBalanceFactory.java	66.66% <ø> (ø)
...seata/discovery/loadbalance/RandomLoadBalance.java	100.00% <ø> (ø)
...a/discovery/loadbalance/RoundRobinLoadBalance.java	66.66% <ø> (ø)
...he/seata/discovery/loadbalance/XIDLoadBalance.java	94.11% <100.00%> (ø)
...ta/discovery/registry/FileRegistryServiceImpl.java	86.66% <100.00%> (+28.04%)	⬆️
...e/seata/discovery/registry/RegistryHeartBeats.java	72.72% <ø> (ø)
...ache/seata/discovery/registry/RegistryService.java	100.00% <100.00%> (+36.11%)	⬆️
.../apache/seata/discovery/registry/RegistryType.java	100.00% <ø> (ø)
... and 19 more

... and 8 files with indirect coverage changes

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[xingfudeshi]

LGTM