feat: save COGs with dask to azure

[wietzesuijker]

This PR introduces Azure Blob Storage support for saving COGs with Dask, complementing the existing AWS S3 support.

• Implements a MultiPartUpload class in _az.py to handle Azure-specific multipart upload operations, including block staging, finalization, and cancellation.
• Adds MultiPartUploadBase in _multipart.py to provide a shared interface for multipart uploads, applicable to both Azure and S3 implementations.
• Updates save_cog_with_dask to recognize Azure URLs and integrate the Azure multipart upload workflow.
• Adds unit tests in tests/test_az.py using mocked Azure SDK to verify functionality specific to Azure Blob Storage.

Here’s a simple test I ran to verify the Azure implementation:

import dask.distributed
import planetary_computer as pc
from odc.geo.cog._tifffile import save_cog_with_dask
from odc.stac import configure_rio, stac_load
from pystac_client import Client

# Setup Dask client for efficient processing
client = dask.distributed.Client()
configure_rio(cloud_defaults=True, client=client)

# Query STAC API for Sentinel-2 data
catalog = Client.open("https://planetarycomputer.microsoft.com/api/stac/v1")
query = catalog.search(
    collections=["sentinel-2-l2a"],
    datetime="2019-06",
    query={"s2:mgrs_tile": dict(eq="06VVN")},
)
items = list(query.items())
print(f"Found {len(items)} datasets")

# Load Sentinel-2 data with specific bands
resolution = 40 
xx = stac_load(
    items,
    bands=["SCL"],
    resolution=resolution,
    chunks={"x": 2048, "y": 2048},
    patch_url=pc.sign,
    dtype="uint16",
    nodata=0,
)

# Select a single time slice for saving
to_save = xx.SCL.isel(time=3)

# Azure Blob Storage details
blob_name = f"SCL-{to_save.time.dt.strftime('%Y%m%d').item()}.tif"
azure_url = f"az://{container}/{blob_name}"


result = save_cog_with_dask(
    to_save,
    dst=f"az://{container}/{blob_name}",
    compression="DEFLATE",
    predictor=2,
    overview_resampling="nearest",
    azure={
        "account_url": f"https://{storage_account}.blob.core.windows.net",
        "credential": sas_token,  # can be blob specific or container wide
    },
    blocksize=[512, 512],
)

# Compute the result to trigger the actual upload
result.compute()
print(f"COG successfully uploaded to: {azure_url}")

While implementing this, I noticed a couple of quirks in the original code:

• Spelling Inconsistencies: Words like finalise vs. finalize were used. I used ise rather than ize.
• Typing Updates: The code inconsistently uses Dict/List from typing vs. built-ins (dict/list). I've changed it to Dict and List since the dev-env.yml specifies python=3.8 (but I hadn't used python 3.8 in ages).

As this is my first PR here, I look forward to feedback and suggestions for improvement!