Break undo if data snapshot is not changed.

[ujjboy]

Ⅰ. Describe what this PR did

• Add DataCompareUtils
• Add some test case.
• Do not execute undo if the before data snapshot is equivalent to the after data snapshot.

Ⅱ. Does this pull request fix one issue?

Part of #1049

[codecov-io]

Codecov Report

Merging #1051 into develop will increase coverage by 0.35%.
The diff coverage is 84.84%.

@@              Coverage Diff              @@
##             develop    #1051      +/-   ##
=============================================
+ Coverage      38.49%   38.85%   +0.35%     
- Complexity      1077     1111      +34     
=============================================
  Files            220      221       +1     
  Lines           8772     8836      +64     
  Branches        1108     1132      +24     
=============================================
+ Hits            3377     3433      +56     
- Misses          4965     4966       +1     
- Partials         430      437       +7

Impacted Files	Coverage Δ	Complexity Δ
...ain/java/io/seata/common/util/CollectionUtils.java	62.5% <100%> (+62.5%)	5 <5> (+5)	⬆️
...seata/rm/datasource/undo/AbstractUndoExecutor.java	82.85% <25%> (-5.03%)	8 <4> (ø)
...rc/main/java/io/seata/common/util/StringUtils.java	12.5% <66.66%> (+4.92%)	10 <4> (+4)	⬆️
.../java/io/seata/rm/datasource/DataCompareUtils.java	90.19% <90.19%> (ø)	24 <24> (?)
...o/seata/rm/datasource/sql/struct/TableRecords.java	38.59% <0%> (+1.75%)	9% <0%> (+1%)	⬆️

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[zhangthen]

Well done.

[xingfudeshi]

LGTM.