[Dubbo-2017]Fix redis auth problem for RedisProtocol

[ningyu1]

What is the purpose of the change

Access redis using a password. #2017

Brief changelog

Fix redis auth problem for RedisProtocol, add parameter db.index for url.

Verifying this change

modify: RedisProtocol.java
modify: RedisRegistry.java
add UT: RedisProtocolTest.testAuthRedis
add UT: RedisProtocolTest.testWrongAuthRedis

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[codecov-io]

Codecov Report

Merging #2018 into master will increase coverage by 1.91%.
The diff coverage is 83.33%.

@@             Coverage Diff              @@
##             master    #2018      +/-   ##
============================================
+ Coverage     52.14%   54.06%   +1.91%     
- Complexity     4902     5148     +246     
============================================
  Files           562      570       +8     
  Lines         25216    25600     +384     
  Branches       4449     4506      +57     
============================================
+ Hits          13150    13840     +690     
+ Misses        10060     9691     -369     
- Partials       2006     2069      +63

Impacted Files	Coverage Δ	Complexity Δ
...apache/dubbo/rpc/protocol/redis/RedisProtocol.java	60.97% <100%> (+0.97%)	7 <0> (+1)	⬆️
...org/apache/dubbo/registry/redis/RedisRegistry.java	32.76% <66.66%> (-0.11%)	16 <0> (ø)
.../remoting/transport/netty4/NettyClientHandler.java	58.33% <0%> (-14.09%)	5% <0%> (ø)
...ache/dubbo/remoting/p2p/support/AbstractGroup.java	45.45% <0%> (-11.37%)	7% <0%> (-1%)
...apache/dubbo/rpc/protocol/rest/BaseRestServer.java	88.88% <0%> (-11.12%)	7% <0%> (-1%)
...ubbo/common/compiler/support/AdaptiveCompiler.java	77.77% <0%> (-11.12%)	3% <0%> (-1%)
...le/src/main/java/com/alibaba/dubbo/rpc/Result.java	22.22% <0%> (-11.12%)	0% <0%> (ø)
...he/dubbo/remoting/transport/netty/NettyClient.java	72.88% <0%> (-10.17%)	12% <0%> (-1%)
...onfig/spring/extension/SpringExtensionFactory.java	75% <0%> (-9.62%)	10% <0%> (+2%)
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-4.17%)	3% <0%> (ø)
... and 70 more

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[kimmking]

You can use StringUtils.isBlank(url.getPassword())？： style to replace if style, reduce reduplicated codes.

[ningyu1]

@kimmking You're right. thank you.
done

[diecui1202]

LGTM.

&READY-TO-MERGE&

[diecui1202]

BTW, need to merge to 2.6.x? @ningyu1

[ningyu1]

@diecui1202 Yes

[ningyu1]

@diecui1202 merge to 2.6.x PR: #2146