Bug 30508: Do not display OPAC message about block from holds when OPACHoldRequests...

Bug 30508: Do not display OPAC message about block from holds when OPACHoldRequests is disabled

This patch adds a check for the OPACHoldRequests to determine whether a
message should be shown to patrons whose account is over the
maxoutstanding limit.

To test, apply the patch and set the "maxoutstanding" system preference
to a low value. Set OPACHoldRequests to "Allow."

- Log in to the OPAC as a patron who has outstanding fines or charges
  which exceed the maxoutstanding value you set.
- You should see a message on the "Your summary" page, "Holds are
  blocked because your fine balance is over the limit."
- Set OPACHoldRequests to "Don't allow" and refresh the "Your summary"
  page in the OPAC. The message should disappear.

Signed-off-by: Amit Gupta <amit.gupta@informaticsglobal.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>