Refactor for publishing to Maven Central

[asarkar]

Summary

Refactor for publishing to Maven Central

Description

1. Merge submodule sql-gremlin into root project.
2. Clean up build.gradle following best practices.
3. Configure publishing to aws.oss.sonatype.org.
4. Upgrade Gradle version and Gradle plugin versions (not dependency versions).
5. Configure build to not fail on checkstyle and SpotBugs violations (due to merging of the sql-gremlin submodule, there are new violations that aren't urgent to fix). Tracked in issue [BUG] Enable static code quality checks #209

[codecov-commenter]

Codecov Report

Merging #208 (3dca66b) into develop (9092f31) will increase coverage by 2.23%.
The diff coverage is 68.00%.

@@             Coverage Diff             @@
##           develop     #208      +/-   ##
===========================================
+ Coverage    65.30%   67.53%   +2.23%     
===========================================
  Files           84      121      +37     
  Lines         4176     5874    +1698     
  Branches       312      585     +273     
===========================================
+ Hits          2727     3967    +1240     
- Misses        1239     1556     +317     
- Partials       210      351     +141     

Impacted Files	Coverage Δ
...neptune/common/gremlindatamodel/MetadataCache.java	30.18% <ø> (ø)
...gremlindatamodel/SchemaHelperGremlinDataModel.java	0.00% <ø> (ø)
...remlindatamodel/resultset/ResultSetGetColumns.java	0.00% <ø> (ø)
...gremlindatamodel/resultset/ResultSetGetTables.java	0.00% <ø> (ø)
...eptune/gremlin/adapter/converter/SqlConverter.java	80.55% <ø> (ø)
...neptune/gremlin/adapter/converter/SqlMetadata.java	78.01% <ø> (ø)
.../gremlin/adapter/converter/SqlTraversalEngine.java	75.67% <ø> (ø)
...adapter/converter/ast/nodes/GremlinSqlFactory.java	77.41% <ø> (ø)
...erter/ast/nodes/operands/GremlinSqlIdentifier.java	63.63% <ø> (ø)
...erter/ast/nodes/operator/GremlinSqlAsOperator.java	41.02% <ø> (ø)
... and 72 more

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[alexey-temnikov]

LGTM!