[update] Replace self without launching a subprocess in windows

Closes: #335, https://github.com/ytdl-org/youtube-dl/issues/28488, https://github.com/ytdl-org/youtube-dl/issues/5810, https://github.com/ytdl-org/youtube-dl/issues/5994

In windows, a running executable cannot be replaced. So, the old updater worked by launching a batch script and then exiting, so that the batch script can replace the executable. However, this caused the above-mentioned issues.

The new method takes advantage of the fact that while the executable cannot be replaced or deleted, it can still be renamed. The current update process on windows is as follows:
1. Delete `yt-dlp.exe.old` if it exists
2. Download the new version as `yt-dlp.exe.new`
3. Rename the running exe to `yt-dlp.exe.old`
4. Rename `yt-dlp.exe.new` to `yt-dlp.exe`
5. Open a shell that deletes `yt-dlp.exe.old` and terminate

While we still use a subprocess, the actual update is already done before the app terminates and the batch script does not print anything to stdout/stderr. So this solves all the above issues

yt_dlp/update.py

@@ -1,7 +1,6 @@
 from __future__ import unicode_literals
 
 import hashlib
-import io
 import json
 import os
 import platform
@@ -147,6 +146,11 @@ def get_sha256sum(bin_or_exe, version):
         directory = os.path.dirname(exe)
         if not os.access(directory, os.W_OK):
             return report_error('no write permissions on %s' % directory, expected=True)
+        try:
+            if os.path.exists(filename + '.old'):
+                os.remove(filename + '.old')
+        except (IOError, OSError):
+            return report_error('unable to remove the old version')
 
         try:
             arch = platform.architecture()[0][:2]
@@ -176,22 +180,24 @@ def get_sha256sum(bin_or_exe, version):
                 return report_error('unable to remove corrupt download')
 
         try:
-            bat = os.path.join(directory, 'yt-dlp-updater.cmd')
-            with io.open(bat, 'w') as batfile:
-                batfile.write('''
-@(
-    echo.Waiting for file handle to be closed ...
-    ping 127.0.0.1 -n 5 -w 1000 > NUL
-    move /Y "%s.new" "%s" > NUL
-    echo.Updated yt-dlp to version %s
-)
-@start /b "" cmd /c del "%%~f0"&exit /b
-                ''' % (exe, exe, version_id))
-
-            subprocess.Popen([bat])  # Continues to run in the background
+            os.rename(exe, exe + '.old')
+        except (IOError, OSError):
+            return report_error('unable to move current version')
+        try:
+            os.rename(exe + '.new', exe)
         except (IOError, OSError):
             report_error('unable to overwrite current version')
+            os.rename(exe + '.old', exe)
+            return
+        try:
+            # Continues to run in the background
+            subprocess.Popen(
+                'ping 127.0.0.1 -n 5 -w 1000 & del /F "%s.old"' % exe,
+                shell=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+            ydl.to_screen('Updated yt-dlp to version %s' % version_id)
             return True  # Exit app
+        except OSError:
+            report_error('unable to delete old version')
 
     # Zip unix package
     elif isinstance(globals().get('__loader__'), zipimporter):