Fix a number of issues related to constructor articles and coding conventions. This may be easier to review commit by commit:

1. Fix small open issues with related articles: 

• Relate coding conventions to diagnostics and editorconfig settings #33341 already addressed in Update coding guidelines #36428.
• Fixes may want variable of INterface type #37294: Add text that the shortened format is valid only when the runtime type matches the variable type.
• Fixes prefer navigation property not shadow ID property #37295: Don't use ID in the sample.
• Fixes score "nil points" #37296: Fix nullable warnings. Other issue comments are incorrect.
• Fixes simplify to code initializer rather than ctor #41748: Change the sample so the constructor is relevant.
• Fixes How to declare static variable above main method in Top Level statement #42858: Add an explanation on declaring variables in top level statements.

2. Fix remaining open issues:

• Fixes Update for C# 13 #43838: Add notes for collection expressions and using primary constructors. Include naming recommendations.
• Fixes Perform an edit pass and add primary constructors #43839 ; Update the overview of constructors to include information on primary constructors.

3. Code review. Update code based on our current style guide.
4. Grammar check and edit pass on all markdown articles.

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