Add serializationConstant

[CrazyHZM]

What is the purpose of the change

Constants is too large, divided into module Constants to manage constants
follow #3967
add SerializationConstants

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #3981 into master will increase coverage by 0.06%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #3981      +/-   ##
============================================
+ Coverage     63.68%   63.74%   +0.06%     
  Complexity       71       71              
============================================
  Files           743      744       +1     
  Lines         32125    32126       +1     
  Branches       5120     5120              
============================================
+ Hits          20458    20480      +22     
+ Misses         9322     9296      -26     
- Partials       2345     2350       +5

Impacted Files	Coverage Δ	Complexity Δ
.../factory/annotation/AnnotationBeanNameBuilder.java	96.96% <ø> (ø)	0 <0> (ø)	⬇️
...dubbo/rpc/cluster/directory/AbstractDirectory.java	96.96% <ø> (ø)	0 <0> (ø)	⬇️
...org/apache/dubbo/rpc/protocol/AbstractInvoker.java	67.74% <ø> (ø)	0 <0> (ø)	⬇️
...he/dubbo/rpc/protocol/ProtocolListenerWrapper.java	89.47% <ø> (ø)	0 <0> (ø)	⬇️
...n/java/org/apache/dubbo/config/ProtocolConfig.java	92.85% <ø> (ø)	0 <0> (ø)	⬇️
...ookeeper/support/AbstractZookeeperTransporter.java	85% <ø> (ø)	0 <0> (ø)	⬇️
.../dubbo/remoting/transport/netty4/NettyChannel.java	65.88% <ø> (ø)	0 <0> (ø)	⬇️
.../rpc/cluster/router/condition/ConditionRouter.java	68.05% <ø> (ø)	0 <0> (ø)	⬇️
...onfig/spring/schema/DubboBeanDefinitionParser.java	67.27% <ø> (ø)	0 <0> (ø)	⬇️
.../org/apache/dubbo/config/MetadataReportConfig.java	92.3% <ø> (ø)	0 <0> (ø)	⬇️
... and 197 more

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[Leishunyu]

LGTM

[beiwei30]

it is indeed a good idea, but it is incomplete solution. Instead, we should examine Constants throughly and classify all constants in it carefully. What I suggest is we should divide this work into four steps:

1. Examine Constants.java and classify throughly.
2. Introduce new sub package 'constants' as what you did, and introduce new Constants classes in it.
3. Start to switch from old Constants to new Constants
4. Remove the old Constants.

I will file one new issue to track this work.

[beiwei30]

It's tracked now by #3137. I will do the step 1 first, after that, we could start to divide the works for step2 and step3

[CrazyHZM]

This is a good plan. After your first step is completed, I will participate in the follow-up work.

[beiwei30]

sure, thanks.