Bootstrap component for file input. Includes label and has predefined sizes and structure for using in foris forms. 

All additional `props` are passed to the `<input type="file">` HTML component.

```js
import { useState } from 'react';

const [files, setFiles] = useState([]);

// Note that files is not an array but FileList.
const label = files.length === 1 ? files[0].name : "Choose file";

<form className="col">
    <FileInput
        files={files}
        label={label}
        helpText="Will be uploaded"
        onChange={event=>setFiles(event.target.files)}
    />
</form>
```

### FileInput with multiple files
```js
import { useState } from 'react';

const [files, setFiles] = useState([]);

// Note that files is not an array but FileList.
const label = files.length > 0 ? Array.from(files).map(file=>file.name).join(", ") : "Choose files";

<form className="col">
    <FileInput
        files={files}
        label={label}
        helpText="Will be uploaded"
        onChange={event=>setFiles(event.target.files)}
        multiple
    />
</form>
```