Rename vue-router-incompatible files

What does this MR do?

Allow viewing iterations within a cadence.

Currently the iteration_form.vue and iteration_report.vue components are not compatible with vue-router (they use pushState and some rails URLs). For the easiest/low-risk solution that doesn't break the existing /iterations page, so copied them and can make the necessary vue-router changes in the new files.

1. Rename the components to be suffixed with _without_vue_router
2. Copy iteration_report.vue, change it so it supports vue-router and injected values for paths/permissions
3. Update other necessary HAML and imports

Once the iteration_cadences feature flag is removed, we can delete the _without_vue_router components, as we'll be using the vue router ones in both places.

Testing

Easiest way is a live_debug in ee/spec/features/groups/iterations/user_views_iteration_cadence_spec.rb

Or to manually test:

1. go to the /iterations page and create some iterations
2. enable iteration_cadences feature flag
3. load the /cadences page (have to edit URL)
4. expand the default cadence
5. click an iteration in the list