rgw: add an inspection to the field of type when assigning user caps

rgw: add an inspection to the field of type when assigning user caps

Bug #13096

This modification adds the check to the field of type of a user's capality while previous versions set it any value. i.e. we limit the option of types to the 9 certain values, which are "users|buckets|metadata|usage|zone|bilog|mdlog|datalog|ops These 9 choosens are found in ceph documents and in source codes.

Signed-off-by: Kongming Wu <wu.kongming@h3c.com>