Generate placeHolders to handle ItemsToken, LimitRowCountToken and so on for rewriting

[tristaZero]

Fixes #2275.

[coveralls]

Pull Request Test Coverage Report for Build 7904

• 44 of 51 (86.27%) changed or added relevant lines in 5 files are covered.
• 103 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.6%) to 55.006%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sharding-core/sharding-core-rewrite/src/main/java/org/apache/shardingsphere/core/rewrite/placeholder/SelectItemsPlaceholder.java	9	10	90.0%
sharding-core/sharding-core-rewrite/src/main/java/org/apache/shardingsphere/core/rewrite/SQLRewriteEngine.java	19	25	76.0%

Files with Coverage Reduction	New Missed Lines	%
sharding-core/sharding-core-rewrite/src/main/java/org/apache/shardingsphere/core/rewrite/SQLRewriteEngine.java	103	41.98%

Totals
Change from base Build 7903:	-0.6%
Covered Lines:	8648
Relevant Lines:	15722

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💛 - Coveralls