Implement rewrite-uri policy in the emulator

We want to add handling rewrite-uri policy in the emulator. [Documentation for policy](https://learn.microsoft.com/en-us/azure/api-management/rewrite-uri-policy)

Start by reading the emulator's existing policy-handling entry points and the linked rewrite-uri policy documentation. Identify the expected behavior and relevant tests, then verify that the emulator handles the documented policy cases.

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