Audit VueRouter instances make sure they supports organization scoped routes

Background

For organizations URLs will be scoped. For example /gitlab-org will be /o/foo-bar/gitlab-org. We need to make sure any instances of VueRouter are set up correctly to deal with this. If they have the base option hard-coded then it will not work. They need to be configured using this guide - https://docs.gitlab.com/development/fe_guide/vue/#vue-router

Completion criteria

• Add developer documentation - !215122 (merged)
• Create an ESLint rule to find usages of hard-coded URLs on the frontend
• Create an Epic and issues for each instance of hard-coded URLs and assign to correct group to fix