Add more test cases from documentation

[andyfengHKU]

This PR also fixes bugs in recursive join

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03 🎉

Comparison is base (da3b552) 91.93% compared to head (6ff18c1) 91.97%.

❗ Current head 6ff18c1 differs from pull request most recent head 14a8761. Consider uploading reports for the commit 14a8761 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1604      +/-   ##
==========================================
+ Coverage   91.93%   91.97%   +0.03%     
==========================================
  Files         704      705       +1     
  Lines       25567    25542      -25     
==========================================
- Hits        23504    23491      -13     
+ Misses       2063     2051      -12     

Impacted Files	Coverage Δ
...ude/processor/operator/recursive_extend/frontier.h	100.00% <ø> (ø)
...ocessor/operator/recursive_extend/recursive_join.h	100.00% <ø> (ø)
...de/processor/operator/recursive_extend/bfs_state.h	100.00% <100.00%> (ø)
...essor/operator/recursive_extend/frontier_scanner.h	100.00% <100.00%> (ø)
...or/operator/recursive_extend/shortest_path_state.h	100.00% <100.00%> (ø)
.../operator/recursive_extend/variable_length_state.h	100.00% <100.00%> (ø)
...c/processor/operator/recursive_extend/frontier.cpp	100.00% <100.00%> (ø)
...sor/operator/recursive_extend/frontier_scanner.cpp	100.00% <100.00%> (ø)
...essor/operator/recursive_extend/recursive_join.cpp	100.00% <100.00%> (ø)
.../recursive_extend/shortest_path_recursive_join.cpp	89.47% <100.00%> (ø)
... and 1 more

... and 2 files with indirect coverage changes

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