text: Title: Option to define snapshot directory name
  Body: **Is your feature request related to a problem? Please describe.**
  
  I prefer to name my snapshot directory `snapshots` instead of `__snapshots__`. I feel the underscores are unnecessary noise.
  
  **Describe the solution you'd like**
  
  A CLI option `--snapshot-dirname <name>`
  
  **Describe alternatives you've considered**
  
  None
  
  **Additional context**
  
  In JS, I use vitest's [resolveSnapshotPath](https://vitest.dev/config/#resolvesnapshotpath) option for the same, it is a bite more flexible as it allows full customization of the path, but I guess I would be happy with a static option just to define the directory name.