WIP add GEBCO bathymetry layer

The GEBCO grid is global, so we can cover all of the QGreenland background this
way (IBCAO only covers a relatively small area around Greenland)

This layer is actually smaller than IBCAO (it has an `int` dtype), even at the
same resolution!

qgreenland/config/datasets/bathymetric_chart.py

@@ -56,3 +56,39 @@
         },
     },
 )
+
+gebco_bathymetric_chart = Dataset(
+    id="gebco_bathymetric_chart",
+    assets=[
+        HttpAsset(
+            id="only",
+            urls=[
+                "https://www.bodc.ac.uk/data/open_download/gebco/gebco_2023/zip/",
+            ],
+        ),
+    ],
+    metadata={
+        "title": "General Bathymetric Chart of the Oceans (GEBCO) Grid 2023",
+        "abstract": (
+            """The GEBCO_2023 Grid is a global terrain model for ocean and land,
+            providing elevation data, in meters, on a 15 arc-second interval
+            grid of 43200 rows x 86400 columns, giving 3,732,480,000 data
+            points. The data values are pixel-centre registered i.e. they refer
+            to elevations, in meters, at the centre of grid cells.
+
+            The grid was published in April 2023 and is the fifth GEBCO grid
+            developed through The Nippon Foundation-GEBCO Seabed 2030
+            Project. This is a collaborative project between the Nippon
+            Foundation of Japan and GEBCO. The Seabed 2030 Project aims to bring
+            together all available bathymetric data to produce the definitive
+            map of the world ocean floor and make it available to all."""
+        ),
+        "citation": {
+            "text": (
+                """GEBCO Compilation Group (2023) GEBCO 2023 Grid
+                (doi:10.5285/f98b053b-0cbc-6c23-e053-6c86abc0af7b)"""
+            ),
+            "url": "https://www.gebco.net/data_and_products/gridded_bathymetry_data/",
+        },
+    },
+)

qgreenland/config/layers/Oceanography/Bathymetry/bathymetric_chart.py

@@ -1,9 +1,12 @@
 from qgreenland.config.datasets.bathymetric_chart import bathymetric_chart as dataset
+from qgreenland.config.datasets.bathymetric_chart import gebco_bathymetric_chart
 from qgreenland.config.helpers.layers.geological_map import make_layer
 from qgreenland.config.helpers.steps.compress_and_add_overviews import (
     compress_and_add_overviews,
 )
+from qgreenland.config.helpers.steps.decompress import decompress_step
 from qgreenland.config.helpers.steps.warp import warp
+from qgreenland.config.helpers.steps.warp_and_cut import warp_and_cut
 from qgreenland.config.project import project
 from qgreenland.models.config.layer import Layer, LayerInput
 
@@ -80,6 +83,43 @@
 )
 
 
+_background_boundary = project.boundaries["background"]
+_background_bbox = _background_boundary.bbox
+gebco_bathymetric_raster = Layer(
+    id="gebco_bathymetric_raster",
+    title="GEBCO depth",
+    description=bathymetric_raster_params["description"],
+    tags=[],
+    style=bathymetric_raster_params["style"],
+    input=LayerInput(
+        dataset=gebco_bathymetric_chart,
+        asset=gebco_bathymetric_chart.assets["only"],
+    ),
+    steps=[
+        decompress_step(input_file="{input_dir}/gebco_2023.zip"),
+        *warp_and_cut(
+            input_file="NETCDF:{input_dir}/GEBCO_2023.nc:elevation",
+            output_file="{output_dir}/bathymetric_chart.tif",
+            reproject_args=(
+                "-te",
+                f"{_background_bbox.min_x} {_background_bbox.min_y} {_background_bbox.max_x} {_background_bbox.max_y}",
+                "-dstnodata",
+                "-9999",
+                "-tr",
+                "400",
+                "400",
+            ),
+            cut_file=project.boundaries["background"].filepath,
+        ),
+        *compress_and_add_overviews(
+            input_file="{input_dir}/bathymetric_chart.tif",
+            output_file="{output_dir}/bathymetric_chart.tif",
+            dtype_is_float=False,
+        ),
+    ],
+)
+
+
 bathymetric_contours = make_layer(
     layer_id=bathymetric_contours_params["id"],
     layer_params=bathymetric_contours_params,