feat: Add HTML manager supporting CDNJS (#5395)

docs/usage/configuration-options.md

lib/datasource/cdnjs/index.ts

lib/manager/cdnurl/extract.ts

lib/manager/html/__fixtures__/axios.json

lib/manager/html/__fixtures__/sample.html

lib/manager/html/__snapshots__/extract.spec.ts.snap

lib/manager/html/extract.spec.ts

lib/manager/html/extract.ts

lib/manager/html/index.ts

lib/manager/html/update.spec.ts

lib/manager/html/update.ts