Comp 282 add observer role

This MR adds the observer role. The main difference is that observers cannot be assigned to an NREN (the assignment is ignored) - and observers have read-only access to all surveys.

The landing page for observers has a table which lists links to the latest survey to each NREN, instead of directly navigating to a specific survey.

requested review from @remco.tukker

assigned to @mohammad.torkashvand

added 1 commit

• 8052422e - correct typo, use parameter instead of current_user

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added 1 commit

• 83c461b9 - be explicit

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resolved all threads

approved this merge request

merged

mentioned in commit 92f817a9