Administrator Entitlement URI accepts only static string

When using the eduPersonEntitlement SAML attribute to set the Administrator Entitlement URI, only a fixed value is accepted.
In some scenarios only a part of the value is fixed, for instance scoped values where you would only want to use the first part of a URN.

As an improvement, it should be possible to accept regular expressions as well.
In order to maintain compatibility, and to avoid introducing an extra “regex or string match” configuration option, this could be done by checking if the value is surrounded by slashes. Pseudo code:

if value = somestring => fixed string match
if value = /somestring.*otherpart/ => regex match