Cache analyzers in Project Settings rather than getting them every frame

[UlyssesWu]

CsprojModifier/src/CsprojModifier/Assets/CsprojModifier/Editor/Features/AddAnalyzerReferenceFeature.cs

Lines 109 to 135 in e82080d

	public override void OnGUI()
	{
	EditorGUILayout.LabelField("Roslyn Analyzer", EditorStyles.boldLabel);
	DrawAnalyzerReferences();
	}
	private void DrawAnalyzerReferences()
	{
	var settings = CsprojModifierSettings.Instance;
	if (RoslynAnalyzerUnityEditorNativeSupport.HasRoslynAnalyzerIdeSupport)
	{
	EditorGUILayout.HelpBox("The current code editor has Roslyn Analyzer IDE support. Roslyn Analyzers are enabled by Unity Editor.", MessageType.Info);
	return;
	}
	settings.EnableAddAnalyzerReferences = EditorGUILayout.ToggleLeft("Add Roslyn Analyzer references to .csproj", settings.EnableAddAnalyzerReferences);
	if (settings.EnableAddAnalyzerReferences)
	{
	using (new EditorGUILayout.VerticalScope(GUI.skin.box))
	{
	var analyzers = GetAnalyzers();
	foreach (var analyzer in analyzers)
	{
	EditorGUILayout.LabelField(analyzer, EditorStyles.label);
	}
	}

It's VERY slow to invoke GetAnalyzers() in every OnGUI call, when the project is large.