Add null to struct fields

[acquamarin]

This PR adds null to struct fields.

[codecov]

Codecov Report

Patch coverage: 98.07% and project coverage change: +0.01 🎉

Comparison is base (4c2ac16) 91.95% compared to head (d7eee9c) 91.97%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1533      +/-   ##
==========================================
+ Coverage   91.95%   91.97%   +0.01%     
==========================================
  Files         687      687              
  Lines       24525    24547      +22     
==========================================
+ Hits        22553    22576      +23     
+ Misses       1972     1971       -1     

Impacted Files	Coverage Δ
src/include/common/null_buffer.h	100.00% <ø> (ø)
...include/function/struct/vector_struct_operations.h	100.00% <ø> (ø)
src/processor/result/factorized_table.cpp	95.21% <ø> (ø)
...c/storage/storage_structure/disk_overflow_file.cpp	92.44% <ø> (ø)
src/function/vector_struct_operations.cpp	92.98% <96.15%> (+2.65%)	⬆️
src/common/types/types.cpp	94.69% <100.00%> (+0.01%)	⬆️
src/common/types/value.cpp	93.20% <100.00%> (+0.05%)	⬆️
src/common/vector/value_vector_utils.cpp	100.00% <100.00%> (ø)
src/storage/copier/rel_copy_executor.cpp	94.46% <100.00%> (ø)
...ge/in_mem_storage_structure/in_mem_node_column.cpp	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.