Refactored edge loader

[siyuan0322]

Make the loading fragment a unified process both for load EV or load E, which is

• Preprocess all edge tables to find vertex tables that need to be deduced,
• Add these deduced vertex tables together with users provided,
• Add the edge tables.

And to make the code reusable, the EFragmentLoader now becomes a utility class and renamed to FragmentLoaderUtils,
mainly focus on the preprocessing works.

[codecov]

Codecov Report

Merging #509 (af1af70) into main (6a3f575) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #509      +/-   ##
==========================================
- Coverage   70.13%   70.09%   -0.05%     
==========================================
  Files          63       63              
  Lines        5646     5645       -1     
==========================================
- Hits         3960     3957       -3     
- Misses       1686     1688       +2     

Impacted Files	Coverage Δ
src/server/vineyardd.cc	81.39% <0.00%> (-4.97%)	⬇️

[siyuan0322]

/hold until the CI of alibaba/GraphScope#855 turned green.

[sighingnow]

Could you please brief the major changes in this pull request in the description?

[siyuan0322]

Could you please brief the major changes in this pull request in the description?

Sorry I only put the description in the GraphScope side. I will copy it here.