[WIP] Adding sketches to collections

[andrewn]

Implementing features in #1115.

Editor API for Collections

Route	Purpose	Restrictions
GET /collections	Fetch current user's collections	Logged in user
GET /:username/collections	Fetch a specific user's collections
POST /collections	Create a new collection	Logged in user
PATCH /collections/:id	Update collection metadata	Logged in user must own collection
DELETE /collections/:id	Delete collection	Logged in user must own collection
POST /collections/:id/:projectId	Add a project to a collection	Logged in user must own collection
DELETE /collections/:id/:projectId	Remove a project from a collection	Logged in user must own collection

To-do

• Editor API for Collections
• Controller tests
• UI to list collections
• UI to view a collection
• UI to create/update/delete a collection
• UI to add/remove a sketch from a collection
• UI tests

Checks

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest master. (If I was asked to make more changes, I have made sure to rebase onto master then too)
• is descriptively named and links to an issue number, i.e. Fixes #123

[andrewn]

WIP UI for listing all collections:

And WIP UI for viewing an indivuidual collection:

The CollectionList and Collection components are mostly copy/pasted from the SketchList component. Once the UI has settled a bit, I'll try and figure out how to remove the duplication in these three components.

[andrewn]

Closing this PR in favour of #1164.