support dubbo.registry.parameters.item3=value3 configuration properties

[xiaoheng1]

What is the purpose of the change

Support the following format configuration properties. such as:

dubbo.registry.parameters.item3=value3

see #8303

Brief changelog

Verifying this change

Checklist

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[codecov-commenter]

Codecov Report

Merging #8308 (806f8ab) into 3.0 (b4d72f9) will decrease coverage by 0.12%.
The diff coverage is 91.66%.

@@             Coverage Diff              @@
##                3.0    #8308      +/-   ##
============================================
- Coverage     64.05%   63.92%   -0.13%     
+ Complexity      313      311       -2     
============================================
  Files          1077     1078       +1     
  Lines         45518    45741     +223     
  Branches       6839     6864      +25     
============================================
+ Hits          29155    29241      +86     
- Misses        13138    13235      +97     
- Partials       3225     3265      +40     

Impacted Files	Coverage Δ
...c/main/java/org/apache/dubbo/config/Constants.java	100.00% <ø> (ø)
...apache/dubbo/common/config/ConfigurationUtils.java	76.59% <91.66%> (+0.45%)	⬆️
...n/java/org/apache/dubbo/config/AbstractConfig.java	80.62% <91.66%> (-0.08%)	⬇️
...nfigcenter/nop/NopDynamicConfigurationFactory.java	50.00% <0.00%> (-50.00%)	⬇️
...nfig/configcenter/nop/NopDynamicConfiguration.java	25.00% <0.00%> (-37.50%)	⬇️
...figcenter/AbstractDynamicConfigurationFactory.java	75.00% <0.00%> (-25.00%)	⬇️
...ache/dubbo/qos/command/util/ServiceCheckUtils.java	0.00% <0.00%> (-11.77%)	⬇️
...in/java/org/apache/dubbo/common/utils/JVMUtil.java	81.13% <0.00%> (-11.33%)	⬇️
...e/dubbo/remoting/transport/netty/NettyChannel.java	52.27% <0.00%> (-7.96%)	⬇️
...mmon/config/configcenter/DynamicConfiguration.java	72.22% <0.00%> (-7.78%)	⬇️
... and 63 more

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[kylixs]

It is better to check argument Map<String, String> values, If it is null or empty, just return

[xiaoheng1]

ok, i will modify it.

[kylixs]

Should we do convert() parameters or not?
For compatibility, convert is needed, but additional parameters will be added, which leads to more url parameters, which is not good. This compatibility does not know what the specific problem is, it is best to deal with it when the parameters are read.

[kylixs]

Some use a.b, some a-b, we will normalize parameter keys later.