[FEATURE REQUEST] Pre-auth rate limiter

### Is your feature request related to a problem? Please describe.

In https://github.com/apache/polaris/pull/278 we added a post-auth rate limiter. We discussed that there should also likely be a pre-auth one because Polaris will have already done some work by the time that rate limiter runs.

### Describe the solution you'd like

A pre-auth rate limiter. This doesn't necessarily have to be implemented _in_ Polaris, but could also be in the form of Docker/Kubernetes config for rate limiting at Envoy/Nginx.

### Describe alternatives you've considered

N/A

### Additional context

https://github.com/apache/polaris/pull/278/files#r1770776479

Review PR #278 and its linked discussion to understand the existing post-auth rate limiter. Decide whether pre-auth limiting belongs in Polaris or in Envoy/Nginx or Docker/Kubernetes configuration; the work is complete when a concrete approach for limiting requests before authentication is defined and implemented.

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