Provide a STAC Catalog

[StefanBrand]

I've found the index of STAC collections here: https://collections.eurodatacube.com/stac/index.json Unfortunately it is not a valid STAC catalog and can therefore not be browsed with tools like STAC Browser.

A valid STAC catalog can be created with minimal effort, e.g.:

{
    "type": "Catalog",
    "stac_version": "1.0.0",
    "id": "eurodatacube-collections-catalog",
    "description": "A STAC catalog that contains all collections available on EuroDataCube.",
    "links": [
        {
            "href": "https://collections.eurodatacube.com/stac/index.json",
            "rel": "self"
        },
        {
            "href": "https://collections.eurodatacube.com/stac/index.json",
            "rel": "root"
        },
        {
            "id": "SENTINEL2_L2A_MOSAIC_120",
            "href": "https://collections.eurodatacube.com/stac/sentinel-s2-l2a-mosaic-120.json",
            "rel": "child"
        },
        ...
    ]
}

I think the relevant change would have to be made to this file:

public-collections/_build/stacIndex.hbs

Lines 1 to 5 in 2f16a10

	[
	{{#each datasets}}
	{"id": "{{OpenEOPID}}", "link": "{{rootUrl}}stac/{{Slug}}.json"}{{#unless @last}},{{/unless}}
	{{/each}}
	]

Something along the lines of:

{
  "type": "Catalog",
  "stac_version": "1.0.0",
  "id": "eurodatacube-collections-catalog",
  "description": "A STAC catalog that contains all collections available on EuroDataCube.",
  "links": [
    {
      "href": "{{rootUrl}}stac/index.json",
      "rel": "self"
    },
    {
      "href": "{{rootUrl}}stac/index.json",
      "rel": "root"
    },
    {{#each datasets}}
      {"id": "{{OpenEOPID}}", "rel": "child", "href": "{{rootUrl}}stac/{{Slug}}.json"}{{#unless @last}},{{/unless}}
    {{/each}}
  ]
}