NLogBeginScopeParser - Reduce allocation for BeginScope with message template

[snakefoot]

No description provided.

[codecov-commenter]

Codecov Report

Merging #451 into master will decrease coverage by 0.12%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master     #451      +/-   ##
==========================================
- Coverage   82.22%   82.09%   -0.13%     
==========================================
  Files          14       14              
  Lines        1198     1212      +14     
  Branches      200      202       +2     
==========================================
+ Hits          985      995      +10     
- Misses        141      144       +3     
- Partials       72       73       +1     

Impacted Files	Coverage Δ
...Extensions.Logging/Logging/NLogBeginScopeParser.cs	66.87% <73.33%> (+0.43%)	⬆️

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