Allow /output_formats to list input formats?

[m-mohr]

Originates from Open-EO/openeo-processes#83
We may need a list of input file formats that a back-end supports to be loaded/imported as data cube with load_user_data (and load_results?). We could rename /output_formats to /formats or /file_formats and change it in a way that input and output formats can be listed. Alternatively, add /input_formats? (Strongly prefer /file_formats at the moment).

[m-mohr]

Discussed on the telco today: Not much feedback, but it seems a list of input formats in addition to the output formats would do it. It should also have parameters to set (and load_user_data Open-EO/openeo-processes#83 needs to accept them), links and gis_data_type. So it's really the same as for output formats.

Example:

{
  "output": {
    "GTiff": {
      "gis_data_types": [
        "raster"
      ],
      "parameters": {
        "tiled": {
          "type": "boolean",
          "description": "This option can be used to force creation of tiled TIFF files [true]. By default [false] stripped TIFF files are created.",
          "default": false
        },
        "compress": {
          "type": "string",
          "description": "Set the compression to use.",
          "default": "none",
          "enum": [
            "JPEG",
            "LZW",
            "DEFLATE",
            "NONE"
          ]
        }
      },
      "links": [
        {
          "href": "https://www.gdal.org/frmt_gtiff.html",
          "rel": "about",
          "title": "GDAL on the GeoTiff file format and storage options"
        }
      ]
    },
    "GPKG": {
      "gis_data_types": [
        "raster",
        "vector"
      ],
      "parameters": {
        "version": {
          "type": "string",
          "description": "Set GeoPackage version. In AUTO mode, this will be equivalent to 1.2 starting with GDAL 2.3.",
          "enum": [
            "auto",
            "1",
            "1.1",
            "1.2"
          ],
          "default": "auto"
        }
      },
      "links": [
        {
          "href": "https://www.gdal.org/drv_geopackage_raster.html",
          "rel": "about",
          "title": "GDAL on GeoPackage for raster data"
        },
        {
          "href": "https://www.gdal.org/drv_geopackage.html",
          "rel": "about",
          "title": "GDAL on GeoPackage for vector data"
        }
      ]
    }
  },
  "input": {
    "GPKG": {
      "gis_data_types": [
        "raster",
        "vector"
      ],
      "parameters": {
        "table": {
          "type": "string",
          "description": "**RASTER ONLY.** Name of the table containing the tiles. If the GeoPackage dataset only contains one table, this option is not necessary. Otherwise, it is required."
        }
      },
      "links": [
        {
          "href": "https://www.gdal.org/drv_geopackage_raster.html",
          "rel": "about",
          "title": "GDAL on GeoPackage for raster data"
        },
        {
          "href": "https://www.gdal.org/drv_geopackage.html",
          "rel": "about",
          "title": "GDAL on GeoPackage for vector data"
        }
      ]
    }
  }
}

[m-mohr]

This is now part of the API specification in the /file_formats endpoint. Response body is defined as in the example above.