Add NQUAD file type, add multiple rdf file scanner

[andyfengHKU]

No description provided.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (3ab6bf1) 91.57% compared to head (5da59c2) 91.57%.

Files	Patch %	Lines
...ssor/operator/persistent/reader/rdf/rdf_reader.cpp	78.57%	9 Missing ⚠️
src/common/copier_config/reader_config.cpp	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2531      +/-   ##
==========================================
- Coverage   91.57%   91.57%   -0.01%     
==========================================
  Files        1029     1029              
  Lines       38040    38059      +19     
==========================================
+ Hits        34836    34852      +16     
- Misses       3204     3207       +3     

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