MB-70730 Fix crash from progress bar getting win size

Previously we used `ioctl` directly to get the terminal size which was
error-prone. We were passing a four character string as a buffer. The
argument for `TIOCGWINSZ` should be four `unsigned short`s long and
`unsigned short` is at least two bytes, so the call was overflowing a
buffer.

This didn't seem to cause a problem in practice, but recently the Python
we ship was upgraded to 3.14 which catches these errors [1]. This caused
a `None` to propagate and later accessed.

We now use `termio.tcgetwinsize` to get the terminal size, and we add
another `None` check.

[1] python/cpython#132915

Change-Id: I6a6a636ca466edd3ef5f711b74002c36522e6044
Reviewed-on: https://review.couchbase.org/c/couchbase-cli/+/240979
Reviewed-by: Lubo Marinski <lubo.marinski@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>
Well-Formed: Restriction Checker

Author: matthallcb

pbar.py

@@ -65,7 +65,7 @@ def get_terminal_width():
         def ioctl_gwinsz(fd):
             """Gets the windows size for a given file descriptor"""
             try:
-                return struct.unpack('hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, '1234'))
+                return termios.tcgetwinsize(fd)
             except BaseException:
                 return None
 
@@ -78,6 +78,9 @@ def ioctl_gwinsz(fd):
             except BaseException:
                 return None, None, None, None
 
+        if window_size is None:
+            return None, None, None, None
+
         return int(window_size[1]), int(window_size[0]), 0, 0
 
     def bold(text):