Add uploaded file to a channel without uploading

[filefilegoadmin]

Sometimes, we might already have a file uploaded to SP, the idea is to be able to create the file without uploading it.

In channels section, we should be able to create a new file by:

1. Entering the file details (name, size, merkle root hash, hash)
2. If the file was uploaded with the UI in the storage section, we could choose it as the file to be uploaded

[filefilegoadmin]

Everything is UI based, there is no need to change anything in the CLI