Ensure every path in routing.yml files has a leading slash

Working on contrib Tour UI running into #2051097: Change "pattern" to "path" in *.routing.yml files I checked for the pattern used by the routing files.

$ find . -name "*.routing.yml" -exec cat {} \; | grep '  path' | cut -c -10 | sort -u
  path: "/
  path: '/
  path: 'a
  path: 'c
  path: 'm
  path: 't
  path: 'u
  path: aj
  path: bl

So we use different quotes or no quote and either use a starting '/' or not.

What should it be?

no quoting

$ find . -name "*.routing.yml" -exec grep -l "  path\: [^\'\"]" {} \;
./modules/block/custom_block/custom_block.routing.yml
./modules/system/tests/modules/ajax_test/ajax_test.routing.yml

Double quote

$ find . -name "*.routing.yml" -exec grep -l '  path: "' {} \;
./modules/system/tests/modules/test_page_test/test_page_test.routing.yml

No starting /

Using

$ find . -name "*.routing.yml" -exec grep  "  path: '" {} \; | cut -c -10 | sort -u

then

$ find . -name "*.routing.yml" -exec grep  "  path: '[abmtu]" {} \;
  path: 'admin/config/system/actions/configure/{action}/delete'
  path: 'admin/structure/config_test/add'
  path: 'admin/structure/config_test/manage/{config_test}'
  path: 'admin/structure/config_test/manage/{config_test}/enable'
  path: 'admin/structure/config_test/manage/{config_test}/disable'
  path: 'admin/structure/config_test/manage/{config_test}/delete'
  path: 'admin/structure/contact/manage/{contact_category}/delete'
  path: 'admin/config/regional/content_translation/translatable/{entity_type}/{field_name}'
  path: 'admin/reports/event/{event_id}'
  path: 'admin/reports/fields'
  path: 'admin/help'
  path: 'admin/help/{name}'
  path: 'admin/config/media/image-styles/manage/{image_style}/delete'
  path: 'admin/config/media/image-styles/manage/{image_style}/effects/{image_effect}/delete'
  path: 'admin/config/regional/language/detection/browser/delete/{browser_langcode}'
  path: 'admin/structure/menu/item/{menu_link}/reset'
  path: 'admin/structure/menu/item/{menu_link}/delete'
  path: 'admin/structure/menu/manage/{menu}/delete'
  path: 'admin/config/search/path/delete/{pid}'
  path: 'user/{user}/shortcuts'
  path: 'admin/config/regional/date-time/formats/manage/{date_format}/delete'
  path: 'admin/config/regional/date-time/locale/{langcode}/reset'
  path: 'admin/modules'
  path: 'admin/modules/list/confirm'
  path: 'admin/index'
  path: 'admin/modules/uninstall'
  path: 'admin/modules/uninstall/confirm'
  path: 'menu_callback_description'
  path: 'url-alter-test/foo'
  path: 'admin/structure/taxonomy/manage/{taxonomy_vocabulary}'
  path: 'tour-test-1'
  path: 'tour-test-1/action'
  path: 'tour-test-2/subpath'