Add controlled components

[panz3r]

Description

This PR introduces 2 new components (DropzoneAreaBase and DropzoneDialogBase) which are the new 'stateless' base for DropzoneArea and DropzoneDialog (which are now simple wrapper to add state).

The 2 base components are exported to allow 'controlled' usages as previously requested.

• Fixes Possibility to override file uploaded #75
• Fixes inputProps not working when setting files prop to an array of files #167

Type of change

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

How Has This Been Tested

• Interactive docs testing

Test Configuration:

• Browser: Edge 81

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules