feat(loader): support kafka as datasource

[liuxiaocs7]

close #95

[codecov]

Codecov Report

Merging #506 (128501d) into master (0aadaa3) will increase coverage by 0.02%.
Report is 1 commits behind head on master.
The diff coverage is 65.42%.

@@             Coverage Diff              @@
##             master     #506      +/-   ##
============================================
+ Coverage     62.47%   62.49%   +0.02%     
- Complexity     1868     1903      +35     
============================================
  Files           260      262       +2     
  Lines          9436     9541     +105     
  Branches        876      886      +10     
============================================
+ Hits           5895     5963      +68     
- Misses         3157     3190      +33     
- Partials        384      388       +4     

Files	Coverage Δ
...a/org/apache/hugegraph/loader/HugeGraphLoader.java	92.53% <100.00%> (+0.11%)	⬆️
...rg/apache/hugegraph/loader/constant/Constants.java	75.00% <ø> (ø)
.../hugegraph/loader/serializer/InputSourceDeser.java	73.91% <100.00%> (+1.18%)	⬆️
...org/apache/hugegraph/loader/source/SourceType.java	100.00% <100.00%> (ø)
...rg/apache/hugegraph/loader/reader/InputReader.java	50.00% <50.00%> (ø)
...che/hugegraph/loader/source/kafka/KafkaSource.java	73.91% <73.91%> (ø)
...che/hugegraph/loader/reader/kafka/KafkaReader.java	77.58% <77.58%> (ø)
...org/apache/hugegraph/loader/util/DataTypeUtil.java	62.73% <0.00%> (-7.41%)	⬇️

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[github-actions]

Due to the lack of activity, the current pr is marked as stale and will be closed after 180 days, any update will remove the stale label

[liuxiaocs7]

Hi, @simon824, @JackyYangPassion, @imbajin, @javeme PTAL, thanks!

[javeme]

nice enhancement

[javeme]

LGTM

[imbajin]

thanks，could add relative doc later~