FEATURE: Drafts view in user profile

* add drafts.json endpoint, user profile tab with drafts stream

* improve drafts stream display in user profile

* truncate excerpts in drafts list, better handling for resume draft action

* improve draft stream SQL query, add rspec tests

* if composer is open, quietly close it when user opens another draft from drafts stream; load PM draft only when user is in /u/username/messages (instead of /u/username)

* cleanup

* linting fixes

* apply prettier styling to modified files

* add client tests for drafts, includes a fixture for drafts.json

* improvements to code following review

* refresh drafts route when user deletes a draft open in the composer while being in the drafts route; minor prettier scss fix

* added more spec tests, deleted an acceptance test for removing drafts that was too finicky, formatting and code style fixes, added appEvent for draft:destroyed

* prettier, eslint fixes

* use "username_lower" from users table, added error handling for rejected promises

* adds guardian spec for can_see_drafts, adds improvements following code review

* move DraftsController spec to its own file

* fix failing drafts qunit test, use getOwner instead of deprecated this.container

* limit test fixture for draft.json testing to new_topic request only

app/controllers/drafts_controller.rb

@@ -0,0 +1,47 @@
+class DraftsController < ApplicationController
+  requires_login
+
+  skip_before_action :check_xhr, :preload_json
+
+  def index
+    params.require(:username)
+    params.permit(:offset)
+    params.permit(:limit)
+
+    user = fetch_user_from_params
+
+    opts = {
+      user: user,
+      offset: params[:offset],
+      limit: params[:limit]
+    }
+
+    guardian.ensure_can_see_drafts!(user)
+    stream = Draft.stream(opts)
+    stream.each do |d|
+      parsed_data = JSON.parse(d.data)
+      if parsed_data
+        if parsed_data['reply']
+          d.raw = parsed_data['reply']
+        end
+        if parsed_data['categoryId'].present? && !d.category_id.present?
+          d.category_id = parsed_data['categoryId']
+        end
+      end
+    end
+
+    help_key = "user_activity.no_drafts"
+    if user == current_user
+      help_key += ".self"
+    else
+      help_key += ".others"
+    end
+
+    render json: {
+      drafts: serialize_data(stream, DraftSerializer),
+      no_results_help: I18n.t(help_key)
+    }
+
+  end
+
+end