Add more flexibility to types of content and preview of useCreateNft hook

[NicolasMahe]

Will be very good to bring flexibility to the type of content and preview. This will make frontend more flexible when creating NFTs.
Currently it's they are only File:

liteflow-js/packages/hooks/src/useCreateNFT.ts

Lines 92 to 93 in 11668f0

	content: File
	preview?: File

The codebase is actually already compatible with File | string as the uploadFile function is already compatible:

liteflow-js/packages/hooks/src/useIPFSUploader.ts

Lines 6 to 18 in 11668f0

	type UploadFn = (
	file: File | string,
	options?: { protected?: boolean },
	) => Promise<string>
	export default function useIPFSUploader(uploadUrl: string): [UploadFn] {
	const upload = useCallback<UploadFn>(
	async (file, options) => {
	if (typeof file === 'string') {
	const gatewayTools = new IPFSGatewayTools()
	const { cid, containsCid } = gatewayTools.containsCID(file)
	return containsCid ? cid : undefined
	}

The hook useUpdateAccount already implement this logic:

liteflow-js/packages/hooks/src/useUpdateAccount.ts

Lines 20 to 22 in 11668f0

	type AccountInput = {
	image?: File | string
	cover?: File | string

For now, only a valid IPFS URI can be put as string, this should be expand to also https URL. The API already accept both ipfs and https URL.

To make the system more generic, the upload function in useIPFSUploader should return not only the CID but the CID with the ipfs prefix: ipfs://CID. This will simplify other part of the codebase.