cubicweb #2545595 add directive bkmk to rest [validation pending]

add directive to include result of bookmark:

:bkmk:`<bookmark-eid>` or :bkmk:`<eid>:<vid>`
prioritynormal
typeenhancement
appeared in<not specified>
done in3.17.0
load0.100
load left0.000
closed by#9060:59a29405688c
patch[ext/rest] add directive bkmk to rest (closes #2545595) [applied]