Change CA2211 from suggestion (analyser default level) to silent.

The codebase has a lot of violations of this rule, reduce the amount of noise by reducing the severity.

.editorconfig

@@ -639,6 +639,7 @@ dotnet_diagnostic.SA1649.severity = none # FileNameMustMatchTypeName
 #### https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/
 
 # Below we enable specific rules by setting severity to warning.
+# Rules are disabled by setting severity to silent (to still allow use in IDE) or none (to prevent all use).
 # Rules are listed below with any options available.
 # Options are commented out if they match the defaults.
 
@@ -920,6 +921,9 @@ dotnet_diagnostic.CA2207.severity = warning
 # Instantiate argument exceptions correctly.
 dotnet_diagnostic.CA2208.severity = warning
 
+# Non-constant fields should not be visible.
+dotnet_diagnostic.CA2211.severity = silent
+
 # Dispose methods should call base class dispose.
 dotnet_diagnostic.CA2215.severity = warning