Audio fix, hint for signal 9, mount font folder

1、修复了音频，现在可以播放声音了；
2、加入了出现“signal 9”错误的提示信息；
3、软件在拥有存储访问权限的情况下，会自动在手机端wps，永中office的外部字体文件夹(AppFiles/Fonts，Fonts)查找字体文件(即挂载这两个目录)，这样就可以不用单独为容器里的wps导入字体了。

pubspec.lock

@@ -49,6 +49,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.1"
+  device_info_plus:
+    dependency: "direct main"
+    description:
+      name: device_info_plus
+      sha256: "86add5ef97215562d2e090535b0a16f197902b10c369c558a100e74ea06e8659"
+      url: "https://pub.dev"
+    source: hosted
+    version: "9.0.3"
+  device_info_plus_platform_interface:
+    dependency: transitive
+    description:
+      name: device_info_plus_platform_interface
+      sha256: d3b01d5868b50ae571cd1dc6e502fc94d956b665756180f7b16ead09e836fd64
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.0"
   equatable:
     dependency: transitive
     description:
@@ -73,6 +89,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      sha256: "5fc22d7c25582e38ad9a8515372cd9a93834027aacf1801cf01164dac0ffa08c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -469,6 +493,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.0.7"
+  win32_registry:
+    dependency: transitive
+    description:
+      name: win32_registry
+      sha256: e4506d60b7244251bc59df15656a3093501c37fb5af02105a944d73eb95be4c9
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.1"
   xdg_directories:
     dependency: transitive
     description: