finish cast string to map

[AEsir777]

• fix nested type
• typo in union data chunk
• update: fix std::string_view{}
  To fix:
• do I need to allow null for struct/map?
• {c:1, c: 2} overwrites the original value (Acceptable)

format	Old	New
MAP(MAP(INT64, INT64), MAP(STRING, STRING)) x 100000	no support	1768
MAP(INT64, STRING)x 50000	4215.386	432.61

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (faa5f98) 89.43% compared to head (a51e7f8) 89.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2201      +/-   ##
==========================================
+ Coverage   89.43%   89.46%   +0.03%     
==========================================
  Files        1007     1007              
  Lines       36317    36385      +68     
==========================================
+ Hits        32479    32553      +74     
+ Misses       3838     3832       -6     

Files	Coverage Δ
src/common/types/types.cpp	91.27% <100.00%> (ø)
src/include/common/string_utils.h	75.00% <ø> (ø)
...rocessor/operator/persistent/reader/csv/driver.cpp	96.41% <100.00%> (+0.78%)	⬆️
src/common/string_utils.cpp	96.36% <92.30%> (-1.26%)	⬇️

... and 3 files with indirect coverage changes

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