Updating permissions checks in the AJAX handler. (#2895)

* Additional checks for enrolling students and removing access plans.

* Additional checks for bulk enrol and checking for duplicates.

* Additional checks.

* Additional checks.

* Removing method that doesn't work. Additional checks on getting course sections.

* Removing method that doesn't work.

* Removing method that doesn't work. Check for getting lesson options.

* Checks for updating lesson title/excerpt.

* Remove lesson check.

* Removing deprecated method.

* Removing deprecated method.

* Additional lesson order check.

* Additional checks for updating auto-enroll courses on a membership.

* Check for editing access plans.

* Changelog.

* Returning nothing.

* Refactor.

* Removing deprecated method.

* Removing log.

* Removing unused methods. Formatting.

* Allow instructor to delete access plans for courses they can edit.

* Refactor to a new method.

* Refactor.

* Fixing phpunit tests.

* Updating snapshot.

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Co-authored-by: branch-sync[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Brian Hogg <brian@bhconsulting.ca>

Author: 3 people

.changelogs/fix_access-plan-remove.yml

@@ -0,0 +1,5 @@
+significance: patch
+type: security
+attributions:
+  - "@mikemyers"
+entry: Additional checks for managing LifterLMS data.