Add support for Playwright driver

This adds support to take full page screenshots when you are using the
[playwright driver](https://github.com/YusukeIwaki/capybara-playwright-driver)

This has been tested in our projects and works like a charm :)

Author: rmehner

lib/capybara-screenshot.rb

@@ -198,6 +198,12 @@ def self.capybara_tmp_path=(path)
   register_driver(:cuprite) do |driver, path|
     driver.render(path, :full => true)
   end
+
+  register_driver(:playwright) do |driver, path|
+    driver.with_playwright_page do |page|
+      page.screenshot(path: path, fullPage: true)
+    end
+  end
 end
 
 # Register filename prefix formatters

spec/unit/saver_spec.rb

@@ -311,6 +311,24 @@
     end
   end
 
+  describe "with playwright driver" do
+    let(:playwright_page_mock) {
+      double('Playwright Page Mock').as_null_object
+    }
+
+    before do
+      allow(capybara_mock).to receive(:current_driver).and_return(:playwright)
+    end
+
+    it 'saves driver screenshot via playwright page with :fullPage => true' do
+      expect(driver_mock).to receive(:with_playwright_page).and_yield(playwright_page_mock)
+      expect(playwright_page_mock).to receive(:screenshot).with(path: screenshot_path, fullPage: true)
+
+      saver.save
+      expect(saver).to be_screenshot_saved
+    end
+  end
+
   describe "with webkit driver" do
     before do
       allow(capybara_mock).to receive(:current_driver).and_return(:webkit)