Merge branch 'add-variables-options' into 'master'

Updates variable value in Entry::Variable to be string rather than array and adds options

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/105502



Merged-by: Grzegorz Bizon <grzegorz@gitlab.com>
Approved-by: Avielle Wolfe <awolfe@gitlab.com>
Approved-by: Grzegorz Bizon <grzegorz@gitlab.com>
Co-authored-by: mgandres <mandres@gitlab.com>
Co-authored-by: Laura Montemayor <lmontemayor@gitlab.com>
Co-authored-by: Kamil Trzciński <ayufan@ayufan.eu>