cephfs-shell: put cmd must accept both paths and validate local_path

cephfs-shell: put cmd must accept both paths and validate local_path

Description:

- `put` command didn't display any error when file at local_path was not
   found. This PR intends to add that check.
   - Rationale: Till now, there used to be a default path of `remote_path` as
                `default='.'` but wasn't mentioned anywhere. It could lead to confusion.
                On top of it, considering put command to be a ssh inspired utlity,
                or any other CLI tool that copies file between filesystems, source
                and destination path are always mandatory. Therefore in order to
                simulate this behavior in cephfs-shell`s command(s), my opinion is
                to make put command accept both the paths.

Fixes: https://tracker.ceph.com/issues/55242
Signed-off-by: dparmar18 <dparmar@redhat.com>