Give CLI users the option to wrap or NOT wrap with directory

[parkan]

It seems that there is some controversy on this subject (#57, #88, #89) -- I'm not sure on the finer points discussed, but in practice I need to emit a root CID without wrapping to match how my other DAGs are processed in estuary. The files come from a system that does not rely on fs level metadata (Internet Archive, file metadata is stored separately in an xml system) so I don't need the wrapper. I think threading this through gives users the flexibility to get the behavior they need.

$ ./dist/cjs/cli/cli.js --pack ../derive-car/test/item/ --output /tmp/item.car
root CID: bafybeidmfmezmxnhnx4pnolbqriolgivs3xqcecsw7lbaiytjwqb4hidr4
  output: /tmp/item.car
$ ipfs-car --list /tmp/item.car 
bafybeidmfmezmxnhnx4pnolbqriolgivs3xqcecsw7lbaiytjwqb4hidr4
bafybeidmfmezmxnhnx4pnolbqriolgivs3xqcecsw7lbaiytjwqb4hidr4/item
...
$ ./dist/cjs/cli/cli.js --wrapWithDirectory false --pack ../derive-car/test/item/ --output /tmp/item.car
root CID: bafybeiar5v44pavnjsnz3tzmgnamrl36sioeakcbndw3t52dvg3crwnogy
  output: /tmp/item.car
$ ipfs-car --list /tmp/item.car 
bafybeiar5v44pavnjsnz3tzmgnamrl36sioeakcbndw3t52dvg3crwnogy
...

The root CID in the second case matches my other tools' output.

[vasco-santos]

LGTM