Update Thunderforest maps

Problem/Motivation

Leaflet More Maps uses old tile format strings for Thunderforest map styles. Besides, those old URLs do not support HTTPS, thus tiles will not even be displayed if the site uses TLS. We should switch to this new URL format, as it is described on the reference page for each style.

Finally, we have the opportunity to include newly created Thunderforest styles in the list.

Proposed resolution

The attached patch changes URL patterns, and adds new Thunderforest map styles.

Remaining tasks

Review patch.

User interface changes

Site builders will see new map styles appear in Leaflet field formatter settings.

API changes

None. Machine names of already existing maps will not change.

Data model changes

None.