Make sure every package supports eslint and run in CI

.gitlab-ci.yml

packages/typescript-example/.eslintignore

packages/typescript-example/.eslintrc.json

packages/typescript-example/package.json

...ges/typescript-example/src/dbp-typescript-example-demo.ts

packages/typescript-example/src/typescript-example.ts

toolkit-showcase/.eslintignore

toolkit-showcase/.eslintrc.json

toolkit-showcase/src/dbp-auth-demo-activity.js

...t-showcase/src/dbp-check-in-place-select-demo-activity.js

toolkit-showcase/src/dbp-common-demo-activity.js

toolkit-showcase/src/dbp-data-table-view-demo-activity.js

toolkit-showcase/src/dbp-demo-template.js

toolkit-showcase/src/dbp-file-handling-demo-activity.js

...dbp-knowledge-base-web-page-element-view-demo-activity.js

toolkit-showcase/src/dbp-language-select-demo-activity.js

toolkit-showcase/src/dbp-matomo-demo-activity.js

toolkit-showcase/src/dbp-notification-demo-activity.js

...kit-showcase/src/dbp-organization-select-demo-activity.js

toolkit-showcase/src/dbp-person-profile-demo-activity.js