Add MarketBoard service and associated interfaces, test and data widget (#1822)

* Add MarketBoard service and associated interfaces, test and data widget
* Dispose of events properly
* Make listings readonly lists + provide internal list for internal use
* Rename CatalogId to ItemId on interfaces, have kept CatalogId internally as it's technically correct
* Removed RetainerOwnerId from the public interface
* Removed NextCatalogId from the public interface
* Updated test text
* Null events in scoped service disposal

Dalamud/Plugin/Services/IMarketBoard.cs

@@ -0,0 +1,64 @@
+namespace Dalamud.Plugin.Services;
+
+using Game.Network.Structures;
+
+/// <summary>
+/// Provides access to market board related events as the client receives/sends them.
+/// </summary>
+public interface IMarketBoard
+{
+    /// <summary>
+    /// A delegate type used with the <see cref="HistoryReceived"/> event.
+    /// </summary>
+    /// <param name="history">The historical listings for a particular item on the market board.</param>
+    public delegate void HistoryReceivedDelegate(IMarketBoardHistory history);
+
+    /// <summary>
+    /// A delegate type used with the <see cref="ItemPurchased"/> event.
+    /// </summary>
+    /// <param name="purchase">The item that has been purchased.</param>
+    public delegate void ItemPurchasedDelegate(IMarketBoardPurchase purchase);
+
+    /// <summary>
+    /// A delegate type used with the <see cref="OfferingsReceived"/> event.
+    /// </summary>
+    /// <param name="currentOfferings">The current offerings for a particular item on the market board.</param>
+    public delegate void OfferingsReceivedDelegate(IMarketBoardCurrentOfferings currentOfferings);
+
+    /// <summary>
+    /// A delegate type used with the <see cref="PurchaseRequested"/> event.
+    /// </summary>
+    /// <param name="purchaseRequested">The details about the item being purchased.</param>
+    public delegate void PurchaseRequestedDelegate(IMarketBoardPurchaseHandler purchaseRequested);
+
+    /// <summary>
+    /// A delegate type used with the <see cref="PurchaseRequested"/> event.
+    /// </summary>
+    /// <param name="taxRates">The new tax rates.</param>
+    public delegate void TaxRatesReceivedDelegate(IMarketTaxRates taxRates);
+
+    /// <summary>
+    /// Event that fires when historical sale listings are received for a specific item on the market board.
+    /// </summary>
+    public event HistoryReceivedDelegate HistoryReceived;
+
+    /// <summary>
+    /// Event that fires when a item is purchased on the market board.
+    /// </summary>
+    public event ItemPurchasedDelegate ItemPurchased;
+
+    /// <summary>
+    /// Event that fires when current offerings are received for a specific item on the market board.
+    /// </summary>
+    public event OfferingsReceivedDelegate OfferingsReceived;
+
+    /// <summary>
+    /// Event that fires when a player requests to purchase an item from the market board.
+    /// </summary>
+    public event PurchaseRequestedDelegate PurchaseRequested;
+
+    /// <summary>
+    /// Event that fires when the client receives new tax rates. These events only occur when accessing a retainer vocate and requesting the tax rates.
+    /// </summary>
+    public event TaxRatesReceivedDelegate TaxRatesReceived;
+}