[Finishes #71448254]
add tooltips and 'edit' links below level entries in script#show.
add 'edit' link in script#show page.
Adding A/B/C testing to hint generation.
Fixes for test cases.
Merge from finished.
Merge remote-tracking branch 'origin/admin_edit_script_levels' into level-builder
tweaks to level builder workflow
levelbuilder updates. auto-admin access for @code.org accounts on staging.
Updated based on Ellen's comment.
Updated get_best_next_hint to get_third_party_hint.
script builder: create new script
level builder changes
Merge finished into level-builder
Drop hints table, add source column to level_source_hints.
Update Stanford hint importing to changed schema.
Changed hints editor to only show crowdsourced hints.
Factored out string constant LevelSourceHint::CROWDSOURCED.
levelbuilder changes
merge finished into level-builder

Conflicts:
	app/assets/stylesheets/application.css.scss
	config/locales/scripts.en.yml
	config/scripts/2-3.script
	config/scripts/custom_levels.json
merge finished into level-builder

Conflicts:
	app/assets/stylesheets/application.css.scss
	config/locales/scripts.en.yml
	config/scripts/2-3.script
	config/scripts/custom_levels.json
levelbuilder changes