Multiple registry #3932

[cvictory]

What is the purpose of the change

support ##3932

Brief changelog

• Add multiple registry module and MultipleRegistry
• Add Dynamic Refresh Abstract Class

Verifying this change

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[chickenlj]

#3599
#3084

[codecov-io]

Codecov Report

Merging #4066 into master will increase coverage by 0.16%.
The diff coverage is 63.19%.

@@             Coverage Diff              @@
##             master    #4066      +/-   ##
============================================
+ Coverage     62.75%   62.91%   +0.16%     
- Complexity      475      504      +29     
============================================
  Files           766      768       +2     
  Lines         32899    33052     +153     
  Branches       5190     5219      +29     
============================================
+ Hits          20647    20796     +149     
+ Misses         9862     9853       -9     
- Partials       2390     2403      +13

Impacted Files	Coverage Δ	Complexity Δ
...bbo/registry/multiple/MultipleRegistryFactory.java	100% <100%> (ø)	2 <2> (?)
...ache/dubbo/registry/multiple/MultipleRegistry.java	62.67% <62.67%> (ø)	20 <20> (?)
...ava/org/apache/dubbo/config/ApplicationConfig.java	91.3% <0%> (-6.29%)	0% <0%> (ø)
...e/dubbo/remoting/transport/netty/NettyChannel.java	57.64% <0%> (-4.71%)	20% <0%> (-1%)
.../java/org/apache/dubbo/config/ReferenceConfig.java	59.48% <0%> (-0.37%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	63.04% <0%> (ø)	0% <0%> (ø)	⬇️
.../main/java/org/apache/dubbo/common/URLBuilder.java	59.21% <0%> (+1.31%)	0% <0%> (ø)	⬇️
...dubbo/metadata/support/AbstractMetadataReport.java	72.83% <0%> (+1.73%)	0% <0%> (ø)	⬇️
... and 7 more

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[chickenlj]

LGTM.

I think this feature can work, but we need to add some docs on how to use it and tuning the performance later