optimize the ReferenceConfig logic

[lixiaojiee]

What is the purpose of the change

extract the resolve file logic

Brief changelog

/dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/ReferenceConfig.java

Verifying this change

ut passed

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[codecov-io]

Codecov Report

Merging #2976 into master will decrease coverage by 0.19%.
The diff coverage is 20.68%.

@@            Coverage Diff            @@
##           master    #2976     +/-   ##
=========================================
- Coverage   64.08%   63.89%   -0.2%     
=========================================
  Files         584      584             
  Lines       26059    26061      +2     
  Branches     4562     4562             
=========================================
- Hits        16700    16651     -49     
- Misses       7184     7226     +42     
- Partials     2175     2184      +9

Impacted Files	Coverage Δ
.../java/org/apache/dubbo/config/ReferenceConfig.java	56.01% <20.68%> (-0.05%)	⬇️
.../remoting/transport/netty4/NettyClientHandler.java	75% <0%> (-13.89%)	⬇️
...ache/dubbo/remoting/transport/AbstractChannel.java	75% <0%> (-12.5%)	⬇️
...che/dubbo/remoting/transport/mina/MinaChannel.java	43.42% <0%> (-10.53%)	⬇️
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-8.34%)	⬇️
.../dubbo/remoting/transport/netty4/NettyChannel.java	61.17% <0%> (-4.71%)	⬇️
...e/dubbo/remoting/transport/netty/NettyChannel.java	57.64% <0%> (-4.71%)	⬇️
.../apache/dubbo/remoting/transport/AbstractPeer.java	58.69% <0%> (-4.35%)	⬇️
...he/dubbo/remoting/transport/netty/NettyServer.java	67.85% <0%> (-3.58%)	⬇️
...org/apache/dubbo/rpc/protocol/AbstractInvoker.java	62.9% <0%> (-3.23%)	⬇️
... and 7 more

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