Refactor: unify CopyNode and CopyRel operator

[ray6080]

• Unify common info/state/functions in CopyNode and CopyRel into a base class.
• Rename Copy to BatchInsert.

[codecov]

Codecov Report

Attention: Patch coverage is 96.18321% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 93.31%. Comparing base (f9e9e29) to head (ca5d82a).

Files	Patch %	Lines
.../processor/operator/persistent/node_batch_insert.h	93.10%	2 Missing ⚠️
...e/processor/operator/persistent/rel_batch_insert.h	88.88%	2 Missing ⚠️
src/processor/operator/index_lookup.cpp	75.00%	2 Missing ⚠️
...processor/operator/persistent/rel_batch_insert.cpp	95.12%	2 Missing ⚠️
...clude/processor/operator/persistent/batch_insert.h	92.30%	1 Missing ⚠️
src/include/storage/wal/wal_record.h	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2955   +/-   ##
=======================================
  Coverage   93.31%   93.31%           
=======================================
  Files        1121     1123    +2     
  Lines       42863    42887   +24     
=======================================
+ Hits        39996    40022   +26     
+ Misses       2867     2865    -2     

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