[bug] conan remote command fails if remotes.json doen't exist

### Environment details

* Operating System+version: Windows 10
* Compiler+version: N/A
* Conan version: 2.0.16
* Python version: 3.10.6

### Steps to reproduce

1. Accidentally remove remotes.json from ~/remotes.json
2. Try to re-add conancenter
3. Got an exception

### Logs

```
$ conan remote add conancenter https://center.conan.io
ERROR: Traceback (most recent call last):
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\cli\cli.py", line 270, in main cli.run(args)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\cli\cli.py", line 180, in run command.run(self._conan_api, args[0][1:])
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\cli\command.py", line 142, in run sub.run(conan_api, parser, *args)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\cli\command.py", line 156, in run info = self._method(conan_api, parent_parser, self._parser, *args)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\cli\commands\remote.py", line 78, in remote_add conan_api.remotes.add(r, force=args.force, index=args.index)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conan\api\subapi\remotes.py", line 66, in add return RemoteRegistry(self._remotes_file).add(remote, force=force, index=index)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conans\client\cache\remote_registry.py", line 163, in add remotes = self._load_remotes()
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conans\client\cache\remote_registry.py", line 151, in _load_remotes return _Remotes.load(self._filename)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\site-packages\conans\client\cache\remote_registry.py", line 33, in load data = json.loads(text)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\json\__init__.py", line 346, in loads return _default_decoder.decode(s)
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\json\decoder.py", line 337, in decode obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "C:\Users\AlexF\AppData\Local\Programs\Python\Python310\lib\json\decoder.py", line 355, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
ERROR: Expecting value: line 1 column 1 (char 0)
```