Proxy checks sanitizer activity prior to pushing

@billwert would like the proxy to warn if sanitizers aren't what we expect when we push. The following changes need to be made.

- [ ] Update our [key generation](https://github.com/Azure/azure-sdk-tools/blob/28c2f15d770b3ed4747da4e700fe17efe31379d2/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Common/SanitizerDictionary.cs#L31) to a hash based on value
- This is necessary because the users POST to the proxy with test-specific additional or removal of sanitizers, and these sanitizers will need a stable id that doesn't change across test runs.
- [ ] Add `Active Sanitizers` to the set of data that is saved with a recording
- [ ] In our `Push` function, [maybe right here](https://github.com/Azure/azure-sdk-tools/blob/28c2f15d770b3ed4747da4e700fe17efe31379d2/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Store/GitStore.cs#L146), check to see that no sanitizers have been REMOVED by examining the previous version of the recording.
- [ ] Add a break-glass for sanitizer protection disable to get around this check if necessary