Add itemTemplate property to FileUpload

[mertsincan]

Used to create custom item elements in the container.

<FileUpload itemTemplate={customItemTemplate} ... />

const customItemTemplate = (file, props) => {
    // file: Current file object.
    // options.onRemove: Event used to remove current file in the container.
    // options.previewElement: The default preview element in the container.
    // options.fileNameElement: The default fileName element in the container.
    // options.sizeElement: The default size element in the container.
    // options.removeElement: The default remove element in the container.
    // options.formatSize: The formated size of file.
    // options.element: Default element created by the component.
    // options.props: component props
}