Add pagination to crops#data_improvement (#4807)

In `CropsController#data_improvement`, paginate `@crops` with
`per_page: 50` so tabs like photos/descriptions do not render all
crops at once. In `data_improvement.html.haml`, render `= will_paginate @crops`.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

app/controllers/crops_controller.rb

@@ -174,7 +174,7 @@ class CropsController < ApplicationController
                Crop.approved.where(public_food_key: [nil, '']).order(plantings_count: :desc)
              else
                Crop.none
-             end
+             end.paginate(page: params[:page], per_page: 50)
   end
 
   private

app/views/crops/data_improvement.html.haml

@@ -11,3 +11,5 @@
   .tab-pane.active
     %h2= "Crops without #{tabs[@active_tab.to_sym]}"
     = render 'crop_list', crops: @crops
+
+    = will_paginate @crops

spec/controllers/crops_controller_spec.rb

@@ -28,6 +28,19 @@ describe CropsController do
     end
   end
 
+  describe "GET data_improvement" do
+    context 'wrangler' do
+      include_context 'login as wrangler'
+
+      it 'fetches the data improvement page and paginates crops with per_page 50' do
+        get :data_improvement
+        expect(response).to be_successful
+        expect(response).to render_template("crops/data_improvement")
+        expect(assigns(:crops).per_page).to eq(50)
+      end
+    end
+  end
+
   describe "GET show" do
     let!(:crop) { create(:crop) }
     let!(:member) { create(:member) }