updated module locked page when module is time locked

updated discussions page to match module locked page used on assignments and
quizzed. updated module locked page to show module's unlock time if module is
timelocked

fixes CNVS-6314

test plan:
- create a discussion topic, assignment, and quiz
- add them to a module that is timelocked
- attempt to view all three as a student
- error pages on all 3 should match, stating the unlock time of the module

Change-Id: I099b645387321b5514d442d477a47ebffdfb88c4
Reviewed-on: https://gerrit.instructure.com/40711
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Matthew Wheeler <mwheeler@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Janelle Seegmiller <jseegmiller@instructure.com>