Redesigned the DiscordBotCore by splitting it into multiple projects. Created a WebUI and preparing to remove the DiscordBot application

DiscordBotCore.PluginManagement.Loading/Exceptions/PluginNotFoundException.cs

@@ -0,0 +1,9 @@
+namespace DiscordBotCore.PluginManagement.Loading.Exceptions;
+
+public class PluginNotFoundException : Exception
+{
+    public PluginNotFoundException(string pluginName) : base($"Plugin {pluginName} was not found") { }
+
+    public PluginNotFoundException(string pluginName, string url, string branch) :
+        base ($"Plugin {pluginName} was not found on {url} (branch: {branch}") { }
+}