Add dagster-azure package with various storage components

Summary:
This adds the following components based on Azure Data Lake Storage
Gen2 (and Azure Blob Storage where appropriate):

- ADLS2FileCache and adls2_file_cache
- ADLS2FileManager
- ADLS2IntermediateStore
- ADLS2ObjectStore
- the adls2_resource providing direct access to Azure Data Lake Storage
- the adls2_system_storage system storage

This is pretty similar to the S3 implementation, the main difference
being configuration: Azure's SDK requires credentials to be passed
explicitly, so the credential is expected in configuration.

Tests currently require an access key to complete any tests marked
'nettest'.

Rename Fake Azure classes and modules to more English-friendly names

Add ADLS2Resource to wrap ADLS2/Blob clients

Fix import order in dagster-azure

Add dagster-azure to install_dev_python_modules make target

Include azure-storage-blob in dagster-azure requirements

Remove unused variable in tests

Don't install dagster-azure as part of install_dev_python_modules make target

Remove accidentally committed Azure Blob object/intermediate store implementations

These work but have no immediate use case and no tests, so seem like an
unnecessary maintenance burden. This commit can be reverted if they're needed!

Wrap potentially incompatible imports to add a custom warning

This centralizes the various azure-storage/azure-core imports and wraps them,
plus the snowflake-connector import, in a try/except block, adding a custom
warning with a suggested solution if the import fails.

Add README to dagster-azure and note about incompatibility to dagster-snowflake's README

Isort

Set buildkite container for dagster-azure tests

Merge pull request #1 from dagster-io/dagster-azure

Set buildkite container for dagster-azure tests

Env variables in buildkite for Azure

Test Plan: bk

Differential Revision: https://dagster.phacility.com/D3238

python_modules/libraries/dagster-azure/dagster_azure/adls2/utils.py

@@ -2,7 +2,7 @@
 
 try:
     # Centralise Azure imports here so we only need to warn in one place
-    from azure.core.exceptions import ResourceNotFoundError
+    from azure.core.exceptions import ResourceNotFoundError  # pylint: disable=unused-import
     from azure.storage.filedatalake import DataLakeServiceClient
 except ImportError:
     msg = (

python_modules/libraries/dagster-azure/dagster_azure/blob/utils.py

@@ -2,8 +2,8 @@
 
 try:
     # Centralise Azure imports here so we only need to warn in one place
-    from azure.core.exceptions import ResourceNotFoundError
-    from azure.storage.blob import generate_blob_sas, BlobServiceClient
+    from azure.core.exceptions import ResourceNotFoundError  # pylint: disable=unused-import
+    from azure.storage.blob import generate_blob_sas, BlobServiceClient  # pylint: disable=unused-import
 except ImportError:
     msg = (
         "Could not import required Azure objects. This probably means you have an old version "