Add ui:DuplicateKeySuffixSeparator

[nickgros]

Reasons for making this change

For my own use case, I needed to change the separator from - to _ between a duplicate key and its unique suffix when using additionalProperties.

To accomplish this, I added a new field to the uiSchema called ui:DuplicateKeySuffixSeparator, which can be used to override the separator with any string.

If the property is undefined, - is used, so the default behavior is unchanged.

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests
  • I've updated docs if needed
• I'm adding a new feature
  • I've updated the playground with an example use of the feature

[epicfaace]

Does this need to be in the uiSchema (i.e. being controlled by a per-field basis) or do you think this would also work if you just made it a form prop (so being controlled on an entire-form basis)?

[nickgros]

Hey @epicfaace, thanks for the quick response.

This could definitely be a prop on the form component. Should that be in addition to, or instead of exposing it via uiSchema?

[nickgros]

Obsoleted by #3048