Update the code that computes effective severity for EditorConfig UX similar to #58461

[mavasani]

We also need to update the code that computes effective severity for EditorConfig UX, I will file a separate issue for the same.

FYI @jmarolf - I'll file an issue for this and assign it to you. I couldn't figure out a trivial fix to thread in CompilationOptions into the below methods used for EditorConfig UX:

roslyn/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Extensions/DiagnosticDescriptorExtensions.cs

Lines 53 to 135 in bf84ccf

	public static bool IsDefinedInEditorConfig(this DiagnosticDescriptor descriptor, AnalyzerConfigOptions analyzerConfigOptions)
	{
	// Check if the option is defined explicitly in the editorconfig
	var diagnosticKey = $"{DotnetDiagnosticPrefix}.{descriptor.Id}.{SeveritySuffix}";
	if (analyzerConfigOptions.TryGetValue(diagnosticKey, out var value) &&
	EditorConfigSeverityStrings.TryParse(value, out var severity))
	{
	return true;
	}
	// Check if the option is defined as part of a bulk configuration
	// Analyzer bulk configuration does not apply to:
	// 1. Disabled by default diagnostics
	// 2. Compiler diagnostics
	// 3. Non-configurable diagnostics
	if (!descriptor.IsEnabledByDefault ||
	descriptor.ImmutableCustomTags().Any(tag => tag is WellKnownDiagnosticTags.Compiler or WellKnownDiagnosticTags.NotConfigurable))
	{
	return false;
	}
	// If user has explicitly configured default severity for the diagnostic category, that should be respected.
	// For example, 'dotnet_analyzer_diagnostic.category-security.severity = error'
	var categoryBasedKey = $"{DotnetAnalyzerDiagnosticPrefix}.{CategoryPrefix}-{descriptor.Category}.{SeveritySuffix}";
	if (analyzerConfigOptions.TryGetValue(categoryBasedKey, out value) &&
	EditorConfigSeverityStrings.TryParse(value, out severity))
	{
	return true;
	}
	// Otherwise, if user has explicitly configured default severity for all analyzer diagnostics, that should be respected.
	// For example, 'dotnet_analyzer_diagnostic.severity = error'
	if (analyzerConfigOptions.TryGetValue(DotnetAnalyzerDiagnosticSeverityKey, out value) &&
	EditorConfigSeverityStrings.TryParse(value, out severity))
	{
	return true;
	}
	// option not defined in editorconfig, assumed to be the default
	return false;
	}
	public static ReportDiagnostic GetEffectiveSeverity(this DiagnosticDescriptor descriptor, AnalyzerConfigOptions analyzerConfigOptions)
	{
	// Check if the option is defined explicitly in the editorconfig
	var diagnosticKey = $"{DotnetDiagnosticPrefix}.{descriptor.Id}.{SeveritySuffix}";
	if (analyzerConfigOptions.TryGetValue(diagnosticKey, out var value) &&
	EditorConfigSeverityStrings.TryParse(value, out var severity))
	{
	return severity;
	}
	// Check if the option is defined as part of a bulk configuration
	// Analyzer bulk configuration does not apply to:
	// 1. Disabled by default diagnostics
	// 2. Compiler diagnostics
	// 3. Non-configurable diagnostics
	if (!descriptor.IsEnabledByDefault ||
	descriptor.ImmutableCustomTags().Any(tag => tag is WellKnownDiagnosticTags.Compiler or WellKnownDiagnosticTags.NotConfigurable))
	{
	return ReportDiagnostic.Default;
	}
	// If user has explicitly configured default severity for the diagnostic category, that should be respected.
	// For example, 'dotnet_analyzer_diagnostic.category-security.severity = error'
	var categoryBasedKey = $"{DotnetAnalyzerDiagnosticPrefix}.{CategoryPrefix}-{descriptor.Category}.{SeveritySuffix}";
	if (analyzerConfigOptions.TryGetValue(categoryBasedKey, out value) &&
	EditorConfigSeverityStrings.TryParse(value, out severity))
	{
	return severity;
	}
	// Otherwise, if user has explicitly configured default severity for all analyzer diagnostics, that should be respected.
	// For example, 'dotnet_analyzer_diagnostic.severity = error'
	if (analyzerConfigOptions.TryGetValue(DotnetAnalyzerDiagnosticSeverityKey, out value) &&
	EditorConfigSeverityStrings.TryParse(value, out severity))
	{
	return severity;
	}
	// option not defined in editorconfig, assumed to be the default
	return ReportDiagnostic.Default;
	}

Originally posted by @mavasani in #58461 (comment)

[sharwell]

⚠️ This feature is likely already working as designed.

#58461 (review)

[mavasani]

I believe this issue can be closed as per Sam's last comment.