Allow bindings with optional values in PostgresBindings

[rgcottrell]

This adds additional methods to PostgresBindings to allow bindings to be created with optionals. The new methods either append a null or delegate to original non optional version of the method. This will make it easier to create PostgresPreparedStatements insert into or update tables with nullable columns. See Issue #509.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 24 lines in your changes missing coverage. Please review.

Project coverage is 61.77%. Comparing base (225c5c4) to head (b3286e4).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/PostgresNIO/New/PostgresQuery.swift	0.00%	24 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #520      +/-   ##
==========================================
+ Coverage   60.23%   61.77%   +1.54%     
==========================================
  Files         125      125              
  Lines        9191    10070     +879     
==========================================
+ Hits         5536     6221     +685     
- Misses       3655     3849     +194     

Files with missing lines	Coverage Δ
Sources/PostgresNIO/New/PostgresQuery.swift	69.32% <0.00%> (-11.45%)	⬇️

... and 74 files with indirect coverage changes

[fabianfett]

Great patch! Thank you!