Support MapRoulette Templating and Mustache Tags

[tannerwuster]

Adds support for Templating in Challenge Instructions and Mustache Tag Replacement 🥸

• Fixes [MapRoulette Integration] Curly braces in instructions aren't replaced #1419
• Fixes [MapRoulette Integration] Support MapRoulette templating in challenge instructions #1423

[tannerwuster]

Here is the templating in action!
Here is the {{osmidenifier}} mustache tag being replaced with the way id.

[tannerwuster]

Now when hovering over osm identifiers it ill highlight what the challenge is talking about. Clicking on it will take you to edit mode

[Bonkles]

A couple of small comments to aid future maintainers! like, oh, say.... me. :)