Resolve "test-selection gap: run system specs when some views changed"

Context

Closes #395017 (closed)

From Draft to Ready

• !115658 (merged) is merged

What does this MR do and why?

When a view gets changed, we try to find feature specs that would test that area of the code.

How do we do this?

The algorithm described in #395017 (closed) was implemented in this MR.

How to set up and validate locally

{
  cat > input.in <<FILE
  app/views/groups/merge_requests.html.haml # Should find spec/features/groups/merge_requests_spec.rb
  app/views/dashboard/_sidebar.html.haml    # Should find spec/features/dashboard/*_spec.rb
  ee/app/views/trials/new.html.haml         # Should find the ee/spec/features/trials/*_spec.rb
  ee/app/views/groups/sso/_tabs.html.haml   # Shouldn't find anything, since the ee/spec/features/groups/sso folder doesn't exist
FILE

  rm -rf output.out
  touch output.out

  ./tooling/bin/view_to_system_specs_mappings input.in output.out; cat output.out
}

The output is as follows:

Click to expand

ee/spec/features/trials/creation_with_lead_spec.rb
ee/spec/features/trials/select_namespace_spec.rb
ee/spec/features/trials/show_trial_banner_spec.rb
ee/spec/features/trials/trial_widget_in_sidebar_spec.rb
spec/features/dashboard/activity_spec.rb
spec/features/dashboard/archived_projects_spec.rb
spec/features/dashboard/datetime_on_tooltips_spec.rb
spec/features/dashboard/group_dashboard_with_external_authorization_service_spec.rb
spec/features/dashboard/group_spec.rb
spec/features/dashboard/groups_list_spec.rb
spec/features/dashboard/issuables_counter_spec.rb
spec/features/dashboard/issues_filter_spec.rb
spec/features/dashboard/issues_spec.rb
spec/features/dashboard/label_filter_spec.rb
spec/features/dashboard/merge_requests_spec.rb
spec/features/dashboard/milestones_spec.rb
spec/features/dashboard/navbar_spec.rb
spec/features/dashboard/project_member_activity_index_spec.rb
spec/features/dashboard/projects_spec.rb
spec/features/dashboard/root_explore_spec.rb
spec/features/dashboard/shortcuts_spec.rb
spec/features/dashboard/snippets_spec.rb
spec/features/dashboard/todos/target_state_spec.rb
spec/features/dashboard/todos/todos_filtering_spec.rb
spec/features/dashboard/todos/todos_sorting_spec.rb
spec/features/dashboard/todos/todos_spec.rb
spec/features/dashboard/user_filters_projects_spec.rb
spec/features/groups/merge_requests_spec.rb

Which contains the expected specs 🎉

MR acceptance checklist

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