Initial Library Loader for .NET Bindings / Update bindings to support newest changes (#763)

* Initial Library Loader

* Load library as part of Model factory

* Dynamically search and find the dlls

* Update tests to use locally built runtimes

* Fix dylib loading, add macos runtime support for sample/tests

* Bypass automatic loading by default.

* Only set CMAKE_OSX_ARCHITECTURES if not already set, allow cross-compile

* Switch Loading again

* Update build scripts for mac/linux

* Update bindings to support newest breaking changes

* Fix build

* Use llmodel for Windows

* Actually, it does need to be libllmodel

* Name

* Remove TFMs, bypass loading by default

* Fix script

* Delete mac script

---------

Co-authored-by: Tim Miller <innerlogic4321@ghmail.com>

gpt4all-bindings/csharp/Gpt4All/LibraryLoader/WindowsLibraryLoader.cs

@@ -0,0 +1,24 @@
+using System.ComponentModel;
+using System.Runtime.InteropServices;
+
+namespace Gpt4All.LibraryLoader;
+
+internal class WindowsLibraryLoader : ILibraryLoader
+{
+    public LoadResult OpenLibrary(string? fileName)
+    {
+        var loadedLib = LoadLibrary(fileName);
+
+        if (loadedLib == IntPtr.Zero)
+        {
+            var errorCode = Marshal.GetLastWin32Error();
+            var errorMessage = new Win32Exception(errorCode).Message;
+            return LoadResult.Failure(errorMessage);
+        }
+
+        return LoadResult.Success;
+    }
+
+    [DllImport("kernel32", SetLastError = true, CharSet = CharSet.Auto)]
+    private static extern IntPtr LoadLibrary([MarshalAs(UnmanagedType.LPWStr)] string? lpFileName);
+}