server : (webui) Enable communication with parent html (if webui is in iframe) (#11940)

* Webui: Enable communication with parent html (if webui is in iframe):
- Listens for "setText" command from parent with "text" and "context" fields. "text" is set in inputMsg, "context" is used as hidden context on the following requests to the llama.cpp server
- On pressing na Escape button sends command "escapePressed" to the parent

Example handling from the parent html side:
- Send command "setText" from parent html to webui in iframe:
const iframe = document.getElementById('askAiIframe');
if (iframe) {
	iframe.contentWindow.postMessage({ command: 'setText', text: text, context: context }, '*');
}

- Listen for Escape key from webui on parent html:
// Listen for escape key event in the iframe
window.addEventListener('keydown', (event) => {
	if (event.key === 'Escape') {
		// Process case when Escape is pressed inside webui
	}
});

* Move the extraContext from storage to app.context.

* Fix formatting.

* add Message.extra

* format + build

* MessageExtraContext

* build

* fix display

* rm console.log

---------

Co-authored-by: igardev <ivailo.gardev@akros.ch>
Co-authored-by: Xuan Son Nguyen <son@huggingface.co>

examples/server/webui/src/utils/app.context.tsx

@@ -25,6 +25,7 @@ interface AppContextValue {
     convId: string | null,
     leafNodeId: Message['id'] | null,
     content: string,
+    extra: Message['extra'],
     onChunk: CallbackGeneratedChunk
   ) => Promise<boolean>;
   stopGenerating: (convId: string) => void;
@@ -32,6 +33,7 @@ interface AppContextValue {
     convId: string,
     parentNodeId: Message['id'], // the parent node of the message to be replaced
     content: string | null,
+    extra: Message['extra'],
     onChunk: CallbackGeneratedChunk
   ) => Promise<void>;
 
@@ -274,6 +276,7 @@ export const AppContextProvider = ({
     convId: string | null,
     leafNodeId: Message['id'] | null,
     content: string,
+    extra: Message['extra'],
     onChunk: CallbackGeneratedChunk
   ): Promise<boolean> => {
     if (isGenerating(convId ?? '') || content.trim().length === 0) return false;
@@ -298,6 +301,7 @@ export const AppContextProvider = ({
         convId,
         role: 'user',
         content,
+        extra,
         parent: leafNodeId,
         children: [],
       },
@@ -324,6 +328,7 @@ export const AppContextProvider = ({
     convId: string,
     parentNodeId: Message['id'], // the parent node of the message to be replaced
     content: string | null,
+    extra: Message['extra'],
     onChunk: CallbackGeneratedChunk
   ) => {
     if (isGenerating(convId)) return;
@@ -339,6 +344,7 @@ export const AppContextProvider = ({
           convId,
           role: 'user',
           content,
+          extra,
           parent: parentNodeId,
           children: [],
         },