feat(client): support user defined OKHTTPClient configs

[zhenyuT]

Follow apache/incubator-hugegraph-commons#140, add a callback builder for user defined configs in (OK)HTTPClient

Before:
(Users)We have no way to modify the (HugeClient(RestClient(HttPClient))) configs, we have to modify hugegraph-common which is really inflexible & hard to use...

After:

            HugeClient.builder(url, graph)
                               .configUser(username, password)
                               .configTimeout(timeout)
                               .configHttpBuilder(x -> x.changeHTTPClientConfigs(....))
                               .build();

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.07%. Comparing base (b066b80) to head (aaf70c9).
Report is 25 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #590      +/-   ##
============================================
- Coverage     62.49%   62.07%   -0.43%     
+ Complexity     1903      930     -973     
============================================
  Files           262       93     -169     
  Lines          9541     4538    -5003     
  Branches        886      529     -357     
============================================
- Hits           5963     2817    -3146     
+ Misses         3190     1512    -1678     
+ Partials        388      209     -179     

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[imbajin]

@JackyYangPassion we need update the revision in root before release

[liuxiaocs7]

+1