Moderators front-end

Closes https://gitlab.com/JOGL/JOGL/-/issues/955, https://gitlab.com/JOGL/JOGL/-/issues/901, https://gitlab.com/JOGL/JOGL/-/issues/848, https://gitlab.com/JOGL/JOGL/-/issues/956, https://gitlab.com/JOGL/JOGL/-/issues/977.

Checklist
Front-end

• create a /admin url
• implement 404 redirection in case user is not moderator
• Code functional BtnDelete with confirmation modal
• implement Delete Btn on user page, appearing only if isModerator
• Same on user cards
• plug BtnDelete action with coming delete user backend endpoint (JOGL!35 (closed))
• insert adapted FormSkillsComponent
• solve last delay bug (btw index names & index ids)
• link it to email system for JOGLers filtered by skills;
• link it to csv downloading btn of the list of JOGLers filtered by skills.

Front-end peripheric tasks done in same branch

• clean /userProfileFormRulesEdit.json and UserCard
• better 404 style
• adapt endpoint call for user deleting itself

Back-end

• algolia disable_index only on test env JOGL!33 (closed)
• Algolia settings fixed so fullstack runs

How to review this MR

• You will need to be able to test both scenarios: moderator or non-moderator, doing so:

bundle exec rails c
User.first.add_role(:moderator) / User.first.remove_role(:moderator)

• Go to the /admin url as a moderator, you should find the dashboard;
• Go to the /admin url as a non-moderator, you should be redirected to 404 as if you had typed a non-existing url;
• Go to the profile page of a user (or its search/members card) as a moderator, you should find a Delete btn and be able to follow through;
• Go to the profile page of a user (or its search/members card) as a non-moderator, you should not even see the Delete btn;
• Test both skills modalities (send email & download csv) in /admin url as a moderator.