Fix breadcrumb links and add collections/schema.html

[kngai]

This PR fixes breadcrumb links and adds the missing schema.html to maintain parity with pygeoapi default theme files. Other minor changes:

• Add truncate(25) to collection titles; similar to pygeoapi default theme
• Remove use of non-existant data['id'] in certain templates; only available in collection/items template
• Add missing translations for schema.html
• Replace with URL pathing with use of data['collections_path'] for path to collections