Creating a taxonomy improperly formats the handle as a slug

[manda-ikaink]

Describe the issue

When creating a new taxonomy, the name is used to auto generate the handle. However, the name in the handle input is auto-formatted like a slug with dashes (-) instead of underscores (_). This will cause a validation error when you attempt to save the taxonomy, forcing you to manually format the handle to replace dashes with underscores.

Screenshots

Version and browser

Version: Master

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