[Issue-653] FLIP-191 extend unified sink interface to support small file compaction

[thekingofcity]

Change log description This FLIP upgrade the new unified Sink from V1 to V2.

Purpose of the change Fix #653

What the code does Upgrade sink code to be compatible with V2.

How to verify it .\gradlew clean build passes.

[codecov[bot]]

Codecov Report

Base: 80.78% // Head: 80.82% // Increases project coverage by +0.03% :tada:

Coverage data is based on head (15df645) compared to base (8b681d2). Patch coverage: 76.92% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #655      +/-   ##
============================================
+ Coverage     80.78%   80.82%   +0.03%     
  Complexity      569      569              
============================================
  Files            60       62       +2     
  Lines          2712     2702      -10     
  Branches        234      233       -1     
============================================
- Hits           2191     2184       -7     
+ Misses          331      328       -3     
  Partials        190      190              

Impacted Files	Coverage Δ
...vega/connectors/flink/sink/PravegaEventWriter.java	68.91% <0.00%> (ø)
...connectors/flink/sink/PravegaTransactionState.java	64.28% <ø> (ø)
...vega/connectors/flink/sink/PravegaSinkBuilder.java	78.12% <70.00%> (-1.19%)	:arrow_down:
...nectors/flink/sink/PravegaTransactionalWriter.java	66.66% <73.33%> (ø)
...onnectors/flink/sink/PravegaTransactionalSink.java	85.71% <85.71%> (ø)
...ravega/connectors/flink/sink/PravegaCommitter.java	65.21% <100.00%> (-6.53%)	:arrow_down:
...ravega/connectors/flink/sink/PravegaEventSink.java	100.00% <100.00%> (ø)
.../io/pravega/connectors/flink/sink/PravegaSink.java	100.00% <100.00%> (+25.00%)	:arrow_up:
... and 1 more

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[crazyzhou]

Since #651 is fixed, this PR can target the latest master branch.