Refactor demo to toolkit showcase

.gitignore

toolkit-showcase/.gitignore

toolkit-showcase/README.md

toolkit-showcase/assets/.htaccess.ejs

toolkit-showcase/assets/Makefile

toolkit-showcase/assets/check-in-place-select.metadata.json

toolkit-showcase/assets/common.metadata.json

toolkit-showcase/assets/data-table-view.metadata.json

toolkit-showcase/assets/dbp-toolkit-showcase.html.ejs

...wcase/assets/dbp-toolkit-showcase.topic.metadata.json.ejs

toolkit-showcase/assets/file-handling.metadata.json

toolkit-showcase/assets/icon-192.png

toolkit-showcase/assets/icon-512.png

...assets/knowledge-base-web-page-element-view.metadata.json

toolkit-showcase/assets/language-select.metadata.json

toolkit-showcase/assets/logo.svg

toolkit-showcase/assets/manifest.json

toolkit-showcase/assets/matomo.metadata.json

toolkit-showcase/assets/notification.metadata.json

toolkit-showcase/assets/person-profile.metadata.json