CLI: admin_only decorator

[sbesson]

Addresses https://trac.openmicroscopy.org.uk/ome/ticket/5137

This PR should extend the admin_only decorator and implement it across all CLI plugins instead of using try/except blocks. Integration tests are also extended to test the admin check.
The only place where the decorator is not used is fs sets --check since the check is conditional to the argument being passed.

/cc @bpindelski

---

--no-rebase

[bpindelski]

Tests pass. I did a git grep SecurityViolation in components/tools/OmeroPy/src/omero/plugins, which gave me some places that might need checking:

• hql.py:231,
• script.py:655,
• sessions.py:395,
• user.py:371

Besides that, code looks good.

[snoopycrimecop]

Conflicting PR. Removed from build OME-5.1-merge-push#550. See the console output for more details.

[sbesson]

Thanks @bpindelski. Reviewed the other plugins and 5710abf should add the admin_only decorator to the group add subcommand. with a corresponding test.

[bpindelski]

Thanks, @sbesson. http://ci.openmicroscopy.org/job/OMERO-5.1-merge-integration-python/lastCompletedBuild/testReport/test.integration.clitest.test_group/TestGroup/testAddAdminOnly/? is green and changes look OK. Good to merge.