feat(server): add option for task role election

[zyxxoo]

Purpose of the PR

• close [Bug] java.lang.ClassCastException: class org.apache.hugegraph.task.DistributedTaskScheduler cannot be cast to class org.apache.hugegraph.task.StandardTaskScheduler #2841

Main Changes

Verifying these changes

• Trivial rework / code cleanup without any test coverage. (No Need)
• Already covered by existing tests, such as (please modify tests here).
• Need tests and can be verified as follows:
  • xxx

Does this PR potentially affect the following parts?

• Dependencies (add/update license info & regenerate_known_dependencies.sh)
• Modify configurations
• The public API
• Other affects (typed here)
• Nope

Documentation Status

• Doc - TODO
• Doc - Done
• Doc - No Need

[codecov]

Codecov Report

❌ Patch coverage is 64.28571% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.90%. Comparing base (3900cc3) to head (89b8625).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...in/java/org/apache/hugegraph/task/TaskManager.java	65.21%	8 Missing ⚠️
...n/java/org/apache/hugegraph/core/GraphManager.java	0.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2843      +/-   ##
============================================
+ Coverage     40.16%   40.90%   +0.73%     
+ Complexity      488      333     -155     
============================================
  Files           747      747              
  Lines         60163    60168       +5     
  Branches       7680     7683       +3     
============================================
+ Hits          24167    24610     +443     
+ Misses        33439    32980     -459     
- Partials       2557     2578      +21     

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