power-policy-service: Add test coverage for provider power

[RobertZ2011]

No description provided.

[Copilot]

Pull request overview

This PR extends the power-policy-service test suite to validate total provider power computations, by making the service instance accessible from tests and asserting expected totals during provider lifecycle flows.

Changes:

• Wrap the power policy Service in a shared Mutex and pass it into test closures via run_test.
• Add assertions in provider tests for compute_total_provider_power_mw() across connect/upgrade/detach/disconnect scenarios.
• Add a consumer test assertion ensuring consumer events don’t affect provider power totals.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
power-policy-service/tests/common/mod.rs	Refactors test harness to share the service via ServiceMutex and pass it into test functions.
power-policy-service/tests/provider.rs	Adds provider-power total assertions throughout provider flow tests.
power-policy-service/tests/consumer.rs	Adds a provider-power total assertion in consumer flow and updates test signatures for the new service argument.
power-policy-service/tests/unconstrained.rs	Updates test signature/imports to accept the new service argument.