Update useBem hook in the way it could receive keys in camel-case

[aluarius]

We want to be able to write in this way:

const computedClass = useBem('va-switch', () => ({
...pick(props, ['readonly', 'disabled', 'leftLabel']),
}))

instead of:

const computedClass = useBem('va-switch', () => ({
...pick(props, ['readonly', 'disabled']),
'left-label': props.leftLabel,
}))

to gain at the end va-switch--left-label for example.