[milestone] Create a cache that listens in on API tokens index if feature is enabled

[derek-ho]

Is your feature request related to a problem?
If API Tokens feature is enabled we will use an allowlist cache which will allow us to check whether a given api token can be used for authc/z. We should only create this cache if the feature is enabled, and it should listen in to index events to keep up to date when an API token is created/revoked/deleted.
What solution would you like?
Similar to existing cache, we create a cache specifically for API tokens
What alternatives have you considered?
Denylist cache, no cache (performance hit)
Do you have any additional context?
None