[firebaseai] Add onTapGesture to close keyboard (#1721)

* add onTapGesture to close keyboard in firebaseai

* Update ImagenScreen.swift

Author: YoungHypo

firebaseai/ChatExample/Screens/ConversationScreen.swift

@@ -78,6 +78,9 @@ struct ConversationScreen: View {
       .focused($focusedField, equals: .message)
       .onSubmit { sendOrStop() }
     }
+    .onTapGesture {
+      focusedField = nil
+    }
     .toolbar {
       ToolbarItem(placement: .primaryAction) {
         Button(action: newChat) {

firebaseai/GenerativeAIMultimodalExample/Screens/PhotoReasoningScreen.swift

@@ -62,6 +62,9 @@ struct PhotoReasoningScreen: View {
         .listStyle(.plain)
       }
     }
+    .onTapGesture {
+      focusedField = nil
+    }
     .navigationTitle("Multimodal example")
     .onAppear {
       focusedField = .message

firebaseai/GenerativeAITextExample/Screens/GenerateContentScreen.swift

@@ -69,6 +69,9 @@ struct GenerateContentScreen: View {
       }
       .listStyle(.plain)
     }
+    .onTapGesture {
+      focusedField = nil
+    }
     .navigationTitle("Text example")
   }
 

firebaseai/ImagenScreen/ImagenScreen.swift

@@ -67,6 +67,9 @@ struct ImagenScreen: View {
         ProgressOverlay()
       }
     }
+    .onTapGesture {
+      focusedField = nil
+    }
     .navigationTitle("Imagen example")
     .onAppear {
       focusedField = .message