backport of elastic#76476

Licensed feature tracking utilizes the existing license level checks to
track when a feature is used. However, some features check the license
level at the start of an operation or when enabling a feature, but then
the tracking only captures the beginning time.

This commit reworks the licensed feature framework to use a new
LicensedFeature class which will eventually replace
XPackLicenseState.Feature values. There are two LicensedFeature
implementations, one for "momentary" features that are tracked just at
the moment they are used, and "persistent" features that are considered
"on" until the feature is untracked. The usage map of tracked features
is cleaned up every hour, and those features that have not been used in
the last 24 hours are removed from tracking.

Not all features are converted to LicensedFeature yet. Instead, a few
features have been converted to demonstrate how it can be done, so that
the rest can be done in parallel at a future time.

Co-authored-by: Tim Vernum <tim@adjective.org>

In 7.x, Elasticsearch automatically enables the file + native realms
if no other (non-reserved) realms are available.

In 8.0 the behaviour is different and they are enabled automatically
on startup unless explicitly disabled.

For this backport the behaviour of asList needs to change to retain
this existing behaviour.