PluralLocalizationFormatter: Fix processing for Singular languages

[axunonb]

Resolves #320

• Fix: Throws FormattingException for Singular languages
• Add unit test for Singular language (Japanese)
• Auto detection only works with more than 1 format argument.
• Is recommended to set CanAutoDetect to false. This will be the default in a future version. Added xmdoc with this hint.

[codecov]

Codecov Report

Base: 96% // Head: 96% // Decreases project coverage by -0% ⚠️

Coverage data is based on head (67c3e0a) compared to base (52850db).
Patch coverage: 100% of modified lines in pull request are covered.

❗ Current head 67c3e0a differs from pull request most recent head 2814d0b. Consider uploading reports for the commit 2814d0b to get more accurate results

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #322   +/-   ##
===================================
- Coverage    96%    96%   -0%     
===================================
  Files        91     91           
  Lines      3186   3183    -3     
===================================
- Hits       3070   3067    -3     
  Misses      116    116           

Impacted Files	Coverage Δ
...rtFormat/Extensions/PluralLocalizationFormatter.cs	92% <100%> (+3%)	⬆️
...rc/SmartFormat/Extensions/LocalizationFormatter.cs	95% <0%> (-5%)	⬇️

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