Adding, destroying and toggling emoji previously lacked services and
instead were performed through methods called on Awardable models.

This led to inconsistencies where relevant todos would be marked as done
only when emoji were awarded through our controllers, but not through
the API. Todos could also be marked as done when an emoji was being
removed.

Behaviour changes

- Awarding emoji through the API will now mark a relevant Todo as done
- Toggling an emoji off (destroying it) through our controllers will no
  longer mark a relevant Todo as done

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/63372

Prefer `json_response` where applicable.

In the Snippets::NotesController the noteable was resolved and
authorized through the :snippet_id, so by passing a :target_id for a
different snippet it was possible to create a note on a snippet
where the user would be unauthorized to do so otherwise.

This fixes the problem by ignoring the :target_id and :target_type from
the request, and using the same noteable for creation and authorization.

Adds frozen string to the following:

* spec/bin/**/*.rb
* spec/config/**/*.rb
* spec/controllers/**/*.rb

xref https://gitlab.com/gitlab-org/gitlab-ce/issues/59758

Updates specs to use new rails5 format.

The old format:
`get :show, { some: params }, { some: headers }`

The new format:
`get :show, params: { some: params }, headers: { some: headers }`

Signed-off-by: Rémy Coutable <remy@rymai.me>