Added naming rule for internal and private fields (#8397)

Author: glen-84

.editorconfig

@@ -159,6 +159,15 @@ dotnet_naming_symbols.static_fields.applicable_accessibilities = private, intern
 dotnet_naming_style.static_prefix_style.required_prefix = s_
 dotnet_naming_style.static_prefix_style.capitalization = camel_case
 
+# Internal and private fields should be _camelCase
+dotnet_naming_rule.camel_case_for_private_internal_fields.severity = warning
+dotnet_naming_rule.camel_case_for_private_internal_fields.symbols = private_internal_fields
+dotnet_naming_rule.camel_case_for_private_internal_fields.style = camel_case_underscore_style
+dotnet_naming_symbols.private_internal_fields.applicable_kinds = field
+dotnet_naming_symbols.private_internal_fields.applicable_accessibilities = private, internal
+dotnet_naming_style.camel_case_underscore_style.required_prefix = _
+dotnet_naming_style.camel_case_underscore_style.capitalization = camel_case
+
 # Name all local variables using camelCase
 dotnet_naming_rule.local_variables_should_be_camel_case.severity = warning
 dotnet_naming_rule.local_variables_should_be_camel_case.symbols = local_variables