Modify previewChipProps type in DropzoneAreaBase and PreviewList

[alichry]

Description

Allow previewChipProps to accept a func that accepts a FileObject and returns ChipProps

Fixes #290

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

In a react app

Test Configuration:

• Browser:

Firefox

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes