Update OATiles to the latest specification changes

[francbartoli]

Description As reported at the OGC OATiles code sprint our demo implementation of the specification is outdated:

• [ ] tilesets should replace tileMatrixSetLinks
• [ ] there should also be a link to a TileSet resource, where the actual item link to tiles will be (/tiles is only the "list of tilesets")
• [ ] The TileJSON should also be changed to be an alternate representation of a particular tileset, as opposed to a describedby / separate metadata resource
• [ ] Also the tileMatrixSetURI should use the TMS register , e.g. http://www.opengis.net/def/tilematrixset/OGC/1.0/WebMercatorQuad
• [ ] the tileMatrixSet key is for a full TMS description, the id should use id

See also this diagram

Steps to Reproduce Steps to reproduce the behavior:

Open the tiles about the lake collection in the demo instance

Expected behavior The closest implementation might be found here

Screenshots/Tracebacks If applicable, add screenshots to help explain your problem.

Environment

• OS:
• Python version:
• pygeoapi version:

Additional context Add any other context about the problem here.