Add truncate collection documents

[erimicel]

Change Summary

The truncate option mentioned in the Typesense docs could be integrated directly into the gem as a shortcut.

Example:

###
# Truncate a collection
#   Deletion returns the number of documents deleted
collection = @typesense.collections['companies'].truncate
ap collection

# {
#   "num_deleted": 125
# }

PR Checklist

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[jasonbosco]

Thank you for the PR!

[jasonbosco]

Available in 3.0.1