App Configuration Python Provider - Load Balancing

[mrm9084]

Description

Adds optional load balancing, default is false.

If enabled a round robin of the config stores endpoints is done when refreshing configurations.

In addition, the order of the config store endpoints is randomized at start and when new ones are found so that multiple instances of the same application don't hit the same stores in the same order.

Also, some static type checking fixes were added from errors seen while updating.

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
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Testing Guidelines

• Pull request includes test coverage for the included changes.

[azure-sdk]

API change check

API changes are not detected in this pull request.

[albertofori]

Is this possible if has_next_client is true?

[mrm9084]

It shouldn't be, but the type checker throws an error if I don't check it. We could make client manager an iterable, but that could cause it's own issues.

[albertofori]

I agree, I would rather we did not make the manager iterable.

So essentially, no matter how we write this, we need the null check?

Even if we put the client check as the sentinel expression for the while loop?

[mrm9084]

The issue is that we need to know the last client used. Most ways like getting the clients and then using them like we did perviously result in us not knowing which one we ended with. Or we would have to mess around on the end side of recording the last one used.

Thoughts?