Three different separation symbols in config file should be changed to one

### Describe the desired feature

The config file `slither.config.json` confusingly uses three different symbols to separate arguments.

```
{
"detectors_to_exclude": "solc-version,similar-names,timestamp,dead-code",
...
"filter_paths": "@openzeppelin/contracts|contracts/itf|contracts/mocks",
...
"solc_remaps": "@openzeppelin=node_modules/@openzeppelin abdk-libraries-solidity=node_modules/abdk-libraries-solidity"
}
```

- ',' (comma)
- '|' (bar)
- ' ' (space)

Using one specific symbol can save some unpleasant debugging time.