feat(mobile): use shared native client (#25942)

* use shared client in dart

fix android

* websocket integration

platform-side headers

update comment

consistent platform check

tweak websocket handling

support streaming

* redundant logging

* fix proguard

* formatting

* handle onProgress

* support videos on ios

* inline return

* improved ios impl

* cleanup

* sync stopForegroundBackup

* voidify

* future already completed

* stream request on android

* outdated ios ws code

* use `choosePrivateKeyAlias`

* return result

* formatting

* update tests

* redundant check

* handle custom headers

* move completer outside of state

* persist auth

* dispose old socket

* use group id for cookies

* redundant headers

* cache global ref

* handle network switching

* handle basic auth

* apply custom headers immediately

* video player update

* fix

* persist url

* potential logout fix

---------

Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/pigeon/network_api.dart

@@ -34,8 +34,14 @@ abstract class NetworkApi {
   void addCertificate(ClientCertData clientData);
 
   @async
-  ClientCertData selectCertificate(ClientCertPrompt promptText);
+  void selectCertificate(ClientCertPrompt promptText);
 
   @async
   void removeCertificate();
+
+  bool hasCertificate();
+
+  int getClientPointer();
+
+  void setRequestHeaders(Map<String, String> headers, List<String> serverUrls);
 }