Make upload directory for winssh communicator configurable

Fixes #8731

plugins/communicators/winssh/communicator.rb

@@ -33,7 +33,7 @@ module VagrantPlugins
 
           tfile = Tempfile.new('vagrant-ssh')
           remote_ext = shell == "powershell" ? "ps1" : "bat"
-          remote_name = "C:\\Windows\\Temp\\#{File.basename(tfile.path)}.#{remote_ext}"
+          remote_name = "#{machine_config_ssh.upload_directory}\\#{File.basename(tfile.path)}.#{remote_ext}"
 
           if shell == "powershell"
             base_cmd = "powershell -File #{remote_name}"

plugins/communicators/winssh/config.rb

@@ -4,9 +4,17 @@ module VagrantPlugins
   module CommunicatorWinSSH
     class Config < VagrantPlugins::Kernel_V2::SSHConfig
 
+      attr_accessor :upload_directory
+
+      def initialize
+        super
+        @upload_directory = UNSET_VALUE
+      end
+
       def finalize!
         @shell = "cmd" if @shell == UNSET_VALUE
         @sudo_command = "%c" if @sudo_command == UNSET_VALUE
+        @upload_directory = "C:\\Windows\\Temp" if @upload_directory == UNSET_VALUE
         if @export_command_template == UNSET_VALUE
           if @shell == "cmd"
             @export_command_template = 'set %ENV_KEY%="%ENV_VALUE%"'

test/unit/plugins/communicators/winssh/communicator_test.rb

@@ -22,7 +22,8 @@ describe VagrantPlugins::CommunicatorWinSSH::Communicator do
     double("winssh",
       insert_key: false,
       export_command_template: export_command_template,
-      shell: 'cmd'
+      shell: 'cmd',
+      upload_directory: "C:\\Windows\\Temp"
     )
   end
   # Configuration mock

website/source/docs/vagrantfile/winssh_settings.html.md

@@ -161,3 +161,8 @@ config.winssh.export_command_template = '$env:%ENV_KEY%="%ENV_VALUE%"'
 with `sudo`. This defaults to `%c` (assumes vagrant user is an administator
 and needs no escalation). The `%c` will be replaced by the command that is
 being executed.
+
+<hr>
+
+`config.winssh.upload_directory` - The upload directory used on the guest
+to store scripts for execute. This is set to `C:\Windows\Temp` by default.