"ipfs add -n FILE" should not require "ipfs init"

#### Version information:

```
go-ipfs version: 0.8.0
Repo version: 11
System version: amd64/linux
Golang version: go1.15.8
```

#### Description:

When adding a file using `-n` (`--only-hash`), there should not be the need to initialize the IPFS repo.
Currently, if you install ipfs but don't run `ipfs init`(or cleanup using `rm -rf ~/.ipfs`), `ipfs add -n FILE` will fail with:
```
Error: no IPFS repo found in /root/.ipfs.
please run: 'ipfs init'
```

So it is correct that no IPFS repo can be found but that should not be required to only hash.