Add AT refresh for Proxy

[JorgeDaboub]

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Related command

This PR refactors portions of the "connectedk8s proxy" command into a helper package to simplify the codebase and improve maintainability for future contributions.

It also removes the ADAL token implementation for Arc proxy authentication. This feature is deprecated, as the extension’s minimum required Azure CLI version is 2.64.0, and the transition to MSAL in the CLI was completed in version 2.30.0.

Lastly, this PR fixes a bug where Access Tokens (AT) passed to the proxy were not refreshed before expiry. Previously, tokens were refreshed alongside the Hybrid Connection (HC), which has a 3-hour expiry, while tokens expire after 1 hour. This change ensures that both are refreshed as needed.

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