feat(tiles): support collection-level OGC API tiles (geodata tiles).

[rkettelerij]

Description

Until now we only supported dataset tiles on /tiles endpoint. This PR adds geodata tiles. These live at the collection-level. So now we also have /collections/<name>/tiles. Both are optional so you can use only dataset tiles, only collection-level tiles or both. All JSON/TileJSON/HTML representations are changed to support this feature.

Type of change

• New feature

Checklist:

• I've double-checked the code in this PR myself
• I've left the code better than before (boy scout rule)
  • remove duplicated projection (EPSG) definitions
  • all templates (also with params) will be validated during startup.
• The code is readable, comments are added that explain hard or non-obvious parts.
• I've expanded/improved the (unit) tests, when applicable
• I've run (unit) tests that prove my solution works
• There's no sensitive information like credentials in my PR