Fixed parsing the output of vswhere

The output of vswhere uses "Ansi" encoding.
It was though decoded via "Utf-8", which raised
an exception in certain cases (i.e. letters like 'ö').

Thus, some visual studio installation could not be found.

Fixes #13281

conans/client/conf/detect_vs.py

@@ -151,7 +151,7 @@ def vswhere(all_=False, prerelease=False, products=None, requires=None, version=
     try:
         from conans.util.runners import check_output_runner
         cmd = cmd_args_to_string(arguments)
-        output = check_output_runner(cmd).strip()
+        output = check_output_runner(cmd, encoding="ansi").strip()
         # Ignore the "description" field, that even decoded contains non valid charsets for json
         # (ignored ones)
         output = "\n".join([line for line in output.splitlines()

conans/util/runners.py

@@ -79,7 +79,7 @@ def detect_runner(command):
     return proc.returncode, "".join(output_buffer)
 
 
-def check_output_runner(cmd, stderr=None):
+def check_output_runner(cmd, stderr=None, encoding="utf-8"):
     # Used to run several utilities, like Pacman detect, AIX version, uname, SCM
     assert isinstance(cmd, str)
     d = tempfile.mkdtemp()
@@ -96,7 +96,7 @@ def check_output_runner(cmd, stderr=None):
             msg = f"Command '{cmd}' failed with errorcode '{process.returncode}'\n{stderr}"
             raise ConanException(msg)
 
-        output = load(tmp_file)
+        output = load(tmp_file, encoding=encoding)
         return output
     finally:
         try: