[File][Bug]Fix Generate File Url API

Currently when the sas token starts with '?' there will be two '?' in
the file url. This commit is to fix the bug.

Author: xiafu-msft

azure-storage-file/azure/storage/file/fileservice.py

@@ -230,7 +230,7 @@ def make_file_url(self, share_name, directory_name, file_name,
             )
 
         if sas_token:
-            url += '?' + sas_token
+            url += (sas_token if sas_token.startswith('?') else '?' + sas_token)
 
         return url
 

tests/file/test_file.py

@@ -172,7 +172,6 @@ def test_make_file_url_with_protocol(self):
         self.assertEqual(res, 'http://' + self.settings.STORAGE_ACCOUNT_NAME
                          + '.file.core.windows.net/vhds/vhd_dir/my.vhd')
 
-    @record
     def test_make_file_url_with_sas(self):
         # Arrange
 
@@ -184,6 +183,17 @@ def test_make_file_url_with_sas(self):
         self.assertEqual(res, 'https://' + self.settings.STORAGE_ACCOUNT_NAME +
                          '.file.core.windows.net/vhds/vhd_dir/my.vhd?sas')
 
+    def test_make_file_url_with_sas_starts_with_question_mark(self):
+        # Arrange
+
+        # Act
+        res = self.fs.make_file_url(
+            'vhds', 'vhd_dir', 'my.vhd', sas_token='?sas')
+
+        # Assert
+        self.assertEqual(res, 'https://' + self.settings.STORAGE_ACCOUNT_NAME +
+                         '.file.core.windows.net/vhds/vhd_dir/my.vhd?sas')
+
     @record
     def test_create_file(self):
         # Arrange