llama.swiftui : update models layout (#4826)

* Updated Models Layout

- Added a models drawer
- Added downloading directly from Hugging Face
- Load custom models from local folder
- Delete models by swiping left

* trimmed trailing white space

* Updated Models Layout

examples/llama.swiftui/llama.swiftui/UI/DownloadButton.swift

@@ -53,6 +53,8 @@ struct DownloadButton: View {
 
                     llamaState.cacheCleared = false
 
+                    let model = Model(name: modelName, url: modelUrl, filename: filename, status: "downloaded")
+                    llamaState.downloadedModels.append(model)
                     status = "downloaded"
                 }
             } catch let err {