Use page.find instead of within in component tests

In component tests, the `within` method is actually an alias to RSpec's
`be_within` matcher, which is used to test numeric ranges. That meant
the tests always passed, even when there were bugs on the page.

In order to use `within` in component tests, we have to use
`page.within`. However, that also fails, since there's no such method
for `Capybara::Node::Simple'` objects, which are used in component
tests.

So we're using `page.find` instead.

See also pull request 945 in https://github.com/github/view_component

spec/components/admin/budgets_wizard/headings/group_switcher_component_spec.rb

@@ -33,9 +33,9 @@ describe Admin::BudgetsWizard::Headings::GroupSwitcherComponent do
     expect(page).to have_content "Showing headings from the Parks group"
     expect(page).to have_button "Manage headings from a different group"
 
-    within "button + ul" do
-      expect(page).to have_link "Recreation"
-      expect(page).to have_link "Entertainment"
+    page.find("button + ul") do |list|
+      expect(list).to have_link "Recreation"
+      expect(list).to have_link "Entertainment"
     end
   end
 end

spec/components/budgets/budget_component_spec.rb

@@ -13,10 +13,10 @@ describe Budgets::BudgetComponent do
 
       render_inline Budgets::BudgetComponent.new(budget)
 
-      within(".budget-header") do
-        expect(page).to have_content("PARTICIPATORY BUDGETS")
-        expect(page).to have_content(budget.name)
-        expect(page).to have_link("Help with participatory budgets")
+      page.find(".budget-header") do |header|
+        expect(header).to have_content "Participatory budgets"
+        expect(header).to have_content budget.name
+        expect(header).to have_link "Help with participatory budgets"
       end
     end
 

spec/components/budgets/subheader_component_spec.rb

@@ -7,9 +7,9 @@ describe Budgets::SubheaderComponent do
 
     render_inline Budgets::SubheaderComponent.new(budget)
 
-    within(".budget-subheader") do
-      expect(page).to have_content "CURRENT PHASE"
-      expect(page).to have_content "Information"
+    page.find(".budget-subheader") do |subheader|
+      expect(subheader).to have_content "Current phase"
+      expect(subheader).to have_content "Information"
     end
   end