`swh-identify` CLI should behave like other checksuming tools and output the name of the file being hashed, i.e., instead of:
```
$ swh-identify hello.c
swh:1:cnt:524175c2bad0b35b975f79284c2f5a6d5eaf2eb4
```
it should do:
```
$ swh-identify hello.c
swh:1:cnt:524175c2bad0b35b975f79284c2f5a6d5eaf2eb4 hello.c
```
(And we should use a `\t` character as separator between the two fields for friendliness toward *nix filters.)