Add Icechunk read-only driver

[Icechunk] (https://icechunk.io/en/stable/overview) is an open-source
transactional storage engine for :ref:`raster.zarr`. Icechunk enables using
Zarr as a true database for array data.

The GDAL Icechunk driver supports datasets using Icechunk v1 and v2 storage
format, hosted on local or cloud storage

It supports:

- "inline chunk references": Zarr chunks are stored directly in a "manifest" file.

- "native chunk references": chunks stored in a file under the :file:`chunks`
  sub-directory of an Icechunk repository

- and "virtual chunk references": chunk content is not directly stored in the
  Icechunk repository. A URL to a remote file, with an offset and length in it,
  is stored instead. This is a mechanism typically used to expose netCDF/HDF5
  files as Zarr, without duplicating actual pixel data. The URL of virtual
  references is automatically morphed into GDAL VSI prefixes (i.e.
  ``https://`` --> ``/vsicurl/https://``, ``s3://`` --> ``/vsis3/``, etc.)

Ex:
```
gdal mdim info /vsis3/icechunk-public-data/v1/glad --config AWS_NO_SIGN_REQUEST YES
```

Uses a /vsiicechunk/ virtual file systems to integrate with the Zarr
driver.

Build requirements: libzstd >= 1.4 and Zarr driver

Also available 2 GDAL CLI commands:

- gdal driver icechunk list-branches
- gdal driver icechunk list-tags

.github/workflows/ubuntu_26.04/expected_gdalinfo_formats.txt

@@ -150,6 +150,7 @@ Supported Formats: (ro:read-only, rw:read-write, +:write from scratch, u:update,
   EHdr -raster- (rw+uv): ESRI .hdr Labelled (*.bil)
   ISCE -raster- (rw+v): ISCE raster
   Zarr -raster,multidimensional raster- (rw+uvs): Zarr (*.zarr)
+  Icechunk -raster,multidimensional raster- (rov): Icechunk
   RCM -raster- (rovs): Radarsat Constellation Mission XML Product
   MiraMonRaster -raster- (rwvs): MiraMon Raster Images (*.rel, *.img)
   HTTP -raster,vector- (ro): HTTP Fetching Wrapper

.github/workflows/windows_conda_expected_gdalinfo_formats.txt

@@ -149,5 +149,6 @@ Supported Formats: (ro:read-only, rw:read-write, +:write from scratch, u:update,
   EHdr -raster- (rw+uv): ESRI .hdr Labelled (*.bil)
   ISCE -raster- (rw+v): ISCE raster
   Zarr -raster,multidimensional raster- (rw+uvs): Zarr (*.zarr)
+  Icechunk -raster,multidimensional raster- (rov): Icechunk
   RCM -raster- (rovs): Radarsat Constellation Mission XML Product
   HTTP -raster,vector- (ro): HTTP Fetching Wrapper

.pre-commit-config.yaml

@@ -76,6 +76,7 @@ repos:
                 frmts/pcidsk/sdk|
                 frmts/grib/degrib/degrib|
                 frmts/grib/degrib/g2clib|
+                frmts/icechunk/generated|
                 gcore/sse2neon.h|
                 port/utf8.h|
                 ogr/ogrsf_frmts/adbc/ogr_adbc_internal.h|

autotest/gdrivers/data/icechunk/physical_chunks/chunks/Q3FTWG07FG2G6Z0JJESG

@@ -0,0 +1 @@
+


autotest/gdrivers/data/icechunk/physical_chunks/chunks/RDW1FCRMX53SJHVRT1EG

@@ -0,0 +1 @@
+

autotest/gdrivers/data/icechunk/regular_array_v1/refs/branch.main/ref.json

@@ -0,0 +1 @@
+{"snapshot":"7D6TE42K99AX675NFRDG"}

autotest/gdrivers/data/icechunk/scalar_array_v1/refs/branch.main/ref.json

@@ -0,0 +1 @@
+{"snapshot":"4HY7Z2Z0STABHN4GKHZG"}

autotest/gdrivers/data/icechunk/scalar_array_v1/refs/tag.my_tag/ref.json

@@ -0,0 +1 @@
+{"snapshot":"4HY7Z2Z0STABHN4GKHZG"}

autotest/gdrivers/data/icechunk/test_icechunk_invalid_zstd/repo

@@ -0,0 +1 @@
+ICE🧊CHUNK