dcap: check for url in some commands

some dcap commands can be executed only with URL suntax

Acked-by: Gerd Behrmann
Target: master, 2.11, 2.10 ( in cobmination with 14d25b2)
Require-book: no
Require-notes: no
(cherry picked from commit fdb056cbc50f4455aba095fe2b5f08643b08d1f4)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>