[File-input] Update component tokens

[aweell]

Changes

• Rename fileItemIconColor as deleteFileItemColor
• Rename hoverFileItemIconBackgroundColor as hoverDeleteFileItemBackgroundColor and update value to color-grey-a-100
• Rename activeFileItemIconBackgroundColor as activeDeleteFileItemBackgroundColor and update value to color-grey-a-300
• Rename focusFileItemIconBackgroundColor as focusDeleteFileItemBackgroundColor

Closes #774

[aidamag]

I am not quite certain about changing fileItemIconColor to deleteFileItemColor because the first one is been applied in the preview icon, not in the delete icon. Maybe to add this deleteFileItemColor token instead of changing an existing one?

[aweell]

I am not quite certain about changing fileItemIconColor to deleteFileItemColor because the first one is been applied in the preview icon, not in the delete icon. Maybe to add this deleteFileItemColor token instead of changing an existing one?

I think we should be using filePreviewIconColor since for that case has this token created for.