Modified to columns in the order of the selected column list

[miyamo2]

This PR modifies ResultResultSet.Columns to be in the order of the selected column list.
However, when SELECT * FROM... or returnsvalue will be sorted by column name as usual.

Issue #146

[codecov]

Codecov Report

Attention: Patch coverage is 89.47368% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 84.80%. Comparing base (2d1cd17) to head (b3f73ca).
Report is 4 commits behind head on main.

Files	Patch %	Lines
stmt_document.go	88.23%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #147      +/-   ##
==========================================
+ Coverage   84.73%   84.80%   +0.06%     
==========================================
  Files           9        9              
  Lines        1173     1191      +18     
==========================================
+ Hits          994     1010      +16     
- Misses        126      127       +1     
- Partials       53       54       +1     

Flag	Coverage Δ
other	79.93% <89.47%> (+0.13%)	⬆️
parsing	23.92% <0.00%> (-0.37%)	⬇️

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