scripts: west_commands: patch: capture subprocess output in apply() method

Pass 'capture_output=True' to the 'subprocess.run()' call in the 'apply()'
method.
This ensures that stdout and stderr are captured, so 'proc.stderr'
is not 'None' when 'self.err()' is called on a failed process.

Example without this patch:
west patch apply --roll-back
error: patch failed: examples/csp_server_client.py:32
error: examples/csp_server_client.py: patch does not apply
ERROR: None
FATAL ERROR: failed to apply patch libcsp/test.patch

Example with this patch:
west patch apply --roll-back
ERROR: b'error: patch failed: examples/csp_server_client.py:32\n
error: examples/csp_server_client.py: patch does not apply\n'
FATAL ERROR: failed to apply patch libcsp/test.patch

Signed-off-by: Mirai SHINJO <oss@mshinjo.com>

Author: mshinjo

scripts/west_commands/patch.py

@@ -391,7 +391,7 @@ def apply(self, args, yml, dst_mods=None):
             self.dbg(f"patching {mod}... ", end="")
             apply_cmd += patch_path
             apply_cmd_list.extend([patch_path])
-            proc = subprocess.run(apply_cmd_list, cwd=mod_path)
+            proc = subprocess.run(apply_cmd_list, capture_output=True, cwd=mod_path)
             if proc.returncode:
                 self.dbg("FAIL")
                 self.err(proc.stderr)