Move investment partial to a component

This way we'll be able to simplify it a little bit.

Note that the original partial didn't include the whole row and only
the cells. Since, most of the time, we include the whole row in
partials, we're slightly modifying the component.

spec/components/admin/budget_investments/row_component_spec.rb

@@ -0,0 +1,9 @@
+require "rails_helper"
+
+describe Admin::BudgetInvestments::RowComponent, :admin do
+  it "uses a JSON request to update visible to valuators" do
+    render_inline Admin::BudgetInvestments::RowComponent.new(create(:budget_investment))
+
+    expect(page).to have_css "form[action$='json'] input[name$='[visible_to_valuators]']"
+  end
+end