[Identity] Enable brokered auth in DAC

[pvaneck]

Description

This adds InteractiveBrowserBrokerCredential silent flow authentication to the end of the DefaultAzureCredential chain. Here, we opt to conditionally add it to the chain only if the broker package is installed.

Additional context: https://gist.github.com/christothes/f8a0dc6249261cb36a6c452717c4e932

Closes: #39966

[azure-sdk]

API Change Check

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azure-identity

[pvaneck]

@xiangyan99 This is the preliminary implementation. Would be good to get your thoughts on:

1. If we should introduce more keyword arguments for broker cred client_id/tenant_id or reuse interactive_browser_client_id and interactive_browser_tenant_id which I am currently doing.
2. Since this is the silent flow and non-interactive, should we introduce this credential to the async DAC (even though it would be run synchronously)?

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