Add code example for CA2226 rule (#49086)

[kurnakovv]

Summary

Fixes #49086

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docs/fundamentals/code-analysis/quality-rules/ca2226.md	CA2226: Operators should have symmetrical overloads

[gewarren]

Snippets5000 error is compiler warnings due to mismatched operators, so I think it's okay to override and merge.

@kurnakovv Actually I think it's better to suppress CS0216 so this large project can continue to build without warnings in the future.

[kurnakovv]

@gewarren I'm not sure how to do it correctly, because this

#pragma warning disable CS0216
// ...
#pragma warning restore CS0216

doesn't work, and this

dotnet_diagnostic.CS0216.severity = none

also doesn't work

I hope this is OK for code example

#if false
// ...
#endif