Add CommandLineParsed to allow initialization based on arguments

src/Faithlife.Build/BuildApp.cs

@@ -66,16 +66,31 @@ public BuildTarget Target(string name)
 		return target;
 	}
 
+	/// <summary>
+	/// Adds an action to execute when the command line arguments have been parsed, but before the target(s) are evaluated and executed.
+	/// </summary>
+	/// <param name="commandLineParsed">The action to execute when the command line arguments have been parsed.</param>
+	public void CommandLineParsed(Action<BuildApp> commandLineParsed)
+	{
+		ArgumentNullException.ThrowIfNull(commandLineParsed);
+
+		m_commandLineParsedActions.Add(commandLineParsed);
+	}
+
 	internal BuildApp(CommandLineApplication app)
 	{
 		m_app = app;
 		m_targets = new List<BuildTarget>();
 		m_flags = new List<BuildFlag>();
 		m_options = new List<BuildOption>();
+		m_commandLineParsedActions = new List<Action<BuildApp>>();
 	}
 
+	internal IReadOnlyList<Action<BuildApp>> CommandLineParsedActions => m_commandLineParsedActions;
+
 	private readonly CommandLineApplication m_app;
 	private readonly List<BuildTarget> m_targets;
 	private readonly List<BuildFlag> m_flags;
 	private readonly List<BuildOption> m_options;
+	private readonly List<Action<BuildApp>> m_commandLineParsedActions;
 }

src/Faithlife.Build/BuildRunner.cs

@@ -60,12 +60,18 @@ public static async Task<int> ExecuteAsync(string[] args, Action<BuildApp> initi
 		var helpFlag = buildApp.AddFlag("-h|-?|--help", "Show build help");
 		var targetsArgument = commandLineApp.Argument("targets", "The targets to build", multipleValues: true);
 
-		var bullseyeTargets = new Targets();
-		foreach (var target in buildApp.Targets)
-			bullseyeTargets.Add(name: target.Name, description: target.Description, dependsOn: target.Dependencies, action: target.RunAsync);
+		commandLineApp.OnParsingComplete(_ =>
+		{
+			foreach (var commandLineParsedAction in buildApp.CommandLineParsedActions)
+				commandLineParsedAction(buildApp);
+		});
 
 		commandLineApp.OnExecuteAsync(async _ =>
 		{
+			var bullseyeTargets = new Targets();
+			foreach (var target in buildApp.Targets)
+				bullseyeTargets.Add(name: target.Name, description: target.Description, dependsOn: target.Dependencies, action: target.RunAsync);
+
 			var targetNames = targetsArgument.Values.WhereNotNull().ToList();
 
 			if (targetNames.Count == 0 && buildApp.Targets.Any(x => x.Name == c_defaultTarget))