[Feature] Default Configuration File Generation Option
### Detailed Description

I would appreciate an option to the executable due to which the current user's configuration would be overwritten with the default configuration of Moe.  Here are some example use cases:

- users who have heavily changed the configuration and intend to reset their settings to the official default values
- users of nightly builds who would like to have access to the latest changes which require multiple changes to the configuration file

Some other editors have a similar feature, as well; Zee, for instance, calls this option `--init`.  The realisation would only require to dump the configuration into the configuration file, thereby truncating and, thus, overwriting all former contents of the file.