[PostgresRowSequence] Make StateMachine private

[fabianfett]

Motivation

• Elements that are private are easier for the compiler to optimize

Changes

• Make PostgresRowSequence.StateMachine private
• Remove unnecessary whitespace

Result

Code that is easier to optimize for the compiler

[codecov-commenter]

Codecov Report

Merging #235 (b6c4db0) into main (cedb5ad) will increase coverage by 4.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #235      +/-   ##
==========================================
+ Coverage   39.82%   43.89%   +4.06%     
==========================================
  Files         116      116              
  Lines        9413     9420       +7     
==========================================
+ Hits         3749     4135     +386     
+ Misses       5664     5285     -379     

Flag	Coverage Δ
unittests	43.89% <100.00%> (+4.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
Sources/PostgresNIO/New/PostgresRowSequence.swift	89.73% <100.00%> (+6.47%)	⬆️
Sources/PostgresNIO/New/PSQLRow-multi-decode.swift	4.44% <0.00%> (+0.19%)	⬆️
Sources/PostgresNIO/Data/PostgresRow.swift	50.00% <0.00%> (+1.02%)	⬆️
...s/PostgresNIO/New/Data/Array+PostgresCodable.swift	94.68% <0.00%> (+1.06%)	⬆️
...rces/PostgresNIO/New/Extensions/Logging+PSQL.swift	19.60% <0.00%> (+1.42%)	⬆️
Sources/PostgresNIO/New/PSQLConnection.swift	30.00% <0.00%> (+2.10%)	⬆️
...ostgresNIO/Deprecated/PostgresMessageDecoder.swift	95.45% <0.00%> (+2.27%)	⬆️
...es/PostgresNIO/New/PSQLBackendMessageDecoder.swift	93.28% <0.00%> (+2.98%)	⬆️
...urces/PostgresNIO/New/Messages/ErrorResponse.swift	32.30% <0.00%> (+3.07%)	⬆️
Sources/PostgresNIO/New/PostgresCell.swift	96.77% <0.00%> (+3.22%)	⬆️
... and 21 more

[gwynne]

Not sure what I’d request changes for in this one… not entirely sure I’m actually approving anything in the first place! 😆 This repo is easily the most active one in Vapor right now….