Refactor of API timeline actions (#3263)

- Increase coverage to exercise all parts of each action
- Move into namespace to share common code
- Misc refactor of each action for smaller methods, simpler code

app/controllers/api/v1/timelines/home_controller.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Api::V1::Timelines
+  class HomeController < BaseController
+    before_action -> { doorkeeper_authorize! :read }, only: [:show]
+    before_action :require_user!, only: [:show]
+
+    def show
+      @statuses = load_statuses
+    end
+
+    private
+
+    def load_statuses
+      cached_home_statuses.tap do |statuses|
+        set_maps(statuses)
+      end
+    end
+
+    def cached_home_statuses
+      cache_collection home_statuses
+    end
+
+    def home_statuses
+      account_home_feed.get(
+        limit_param(DEFAULT_STATUSES_LIMIT),
+        params[:max_id],
+        params[:since_id]
+      )
+    end
+
+    def account_home_feed
+      Feed.new(:home, current_account)
+    end
+
+    def next_path
+      api_v1_timelines_home_url pagination_params(max_id: @statuses.last.id)
+    end
+
+    def prev_path
+      api_v1_timelines_home_url pagination_params(since_id: @statuses.first.id)
+    end
+  end
+end