REQUEST: Audit Device(s) track requests to /sys/rekey endpoints

[stuartpurgavie]

Is your feature request related to a problem? Please describe.
I recently ran into an issue with the sys/rekey endpoint(s) as discussed in the forums. When I ran into this issue, the first thing I wanted to check were the logs generated from the audit device. Unfortunately, because these endpoints are unauthenticated, there were no responses to inspect.

Describe the solution you'd like
Ideally, when sys/rekey is hit, I would like to be able to see what Vault has done with those requests and what responses it has made, for troubleshooting purposes.

Additional context
This is possibly related to #2244 as generate-root is in a similar place of unauthenticated endpoints not being audited. Arguably, both Re-key and Root Generation should be audited as alerts could be dynamically generated from the audit.

[aphorise]

This is still applicable as of 1.11.x - any chance this will be addressed in a future release @ncabatoff