Add e2e tests

[taslangraham]

The ability to restrict email template access by user groups was introduced via issue #10403 (sub-task #10571). To ensure proper functionality, we need to add end-to-end Cypress tests.

Currently, the code for this feature has not yet been merged and is still hosted on my fork of the repositories (more context here). As a result, the pull requests for the tests are also located on my fork, pending the eventual merge of all related code into the original repositories.

pkp-lib: taslangraham#6
ojs: taslangraham/ojs#2
omp: taslangraham/omp#2
ops: taslangraham/ops#2