Feature#2715

[sunbufu]

Fixes #2715.

Changes proposed in this pull request:

1. add getQueryResultMetaData() method on QueryResult.
2. add QueryResultMetaData on StreamQueryResult class.
3. modify AggregationDistinctQueryResult constructor to use queryResultMetaData instead of columnLabelAndIndexMap.
4. use HashMultimap instead of TreeMap on QueryResultMetaData.
5. modify unit test class.
6. add integrated test.

[coveralls]

Pull Request Test Coverage Report for Build 9124

• 41 of 41 (100.0%) changed or added relevant lines in 6 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.8%) to 64.902%

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Files with Coverage Reduction	New Missed Lines	%
sharding-orchestration/sharding-orchestration-core/src/main/java/org/apache/shardingsphere/orchestration/internal/util/IpUtils.java	3	76.0%

Totals
Change from base Build 231:	0.8%
Covered Lines:	9168
Relevant Lines:	14126

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💛 - Coveralls