#2039 Accept block for download_links
#2039 Ensure that download_links supports stabby proc syntax `-> {}` by using `instance_exec`
#2039 Remove unused restricted AdminUser leftover from manual testing.
Merge pull request #2040 from creativecommunion/2039-accept-block-for-download_links

#2039 Accept block for download_links
add tests to illustrate symbol leakage problems
utilize `default_url_options` to inject expected query params
fix batch action symbol leakage