feat: FCM HTTP v1 API changes (#9629)

Fixes https://linear.app/chatwoot/issue/CW-3210/legacy-firebase-changes

app/services/notification/fcm_service.rb

@@ -0,0 +1,40 @@
+class Notification::FcmService
+  SCOPES = ['https://www.googleapis.com/auth/firebase.messaging'].freeze
+
+  def initialize(project_id, credentials)
+    @project_id = project_id
+    @credentials = credentials
+    @token_info = nil
+  end
+
+  def fcm_client
+    FCM.new(current_token, credentials_path, @project_id)
+  end
+
+  private
+
+  def current_token
+    @token_info = generate_token if @token_info.nil? || token_expired?
+    @token_info[:token]
+  end
+
+  def token_expired?
+    Time.zone.now >= @token_info[:expires_at]
+  end
+
+  def generate_token
+    authorizer = Google::Auth::ServiceAccountCredentials.make_creds(
+      json_key_io: credentials_path,
+      scope: SCOPES
+    )
+    token = authorizer.fetch_access_token!
+    {
+      token: token['access_token'],
+      expires_at: Time.zone.now + token['expires_in'].to_i
+    }
+  end
+
+  def credentials_path
+    StringIO.new(@credentials)
+  end
+end