Overhaul Azure storage infrastructure.

[jmchilton]

• Upgrade away from legacy Azure APIs for azure_blob object store. Eliminate some hacks and fix a bunch of things I discovered during testing. I also think these have been broken since the object store selection PR was merged years ago at this point 😅.
• Implement short-term read-only tokens for azure storage blobs.
• Implement an Azure file source using the relevant pyfilesystem plugins. I don't love everything the plugin implementation does but I guess we should assume they did it that way for a reason.
• A lot more testing for the object store ("unit" testing that tests the unit against actual APIs if you have keys and integration with the rest of Galaxy) and some initial testing for the new file source plugins.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[mvdbeek]

Thank you @jmchilton!