Set quarkus-cache properties at runtime

[mikethecalamity]

Description

The properties for the quarkus-cache extension look like they should be settable at runtime. At the very least: enabled, initial-capacity, maximum-size, expire-after-write, expire-after-access.

Implementation ideas

No response

[quarkus-bot]

/cc @gwenneg(cache)

[geoand]

@gwenneg I'll let you decide whether you want to keep this or #28966 open.
There is no reason to have both issues around

[gwenneg]

This issue covers more config keys so I'm closing the other one.

[gwenneg]

There are at least two approaches to make some of the config values overridable at run time:

1. Changing the config phase of these values, which are currently declared in CacheConfig, from BUILD_TIME to RUN_TIME. This isn't as easy as it sounds though because cache instances are constructed at build time using recorded bytecode which is eventually run from a static initializer.

2. Taking advantage of Caffeine's Policy which could be used from new CaffeineCache methods to override maximum-size, expire-after-write and expire-after-access. For instance, CaffeineCache#setMaximumSize could be called at any time (application startup or later) to change the max size of a cache. This could be added to the Quarkus dev UI by the extension, but also exposed through a REST API (or any other mean) by a Quarkus app if relevant.

I am exploring a bit these two approaches. Feel free to suggest a third idea 😃

[gwenneg]

I've submitted a PR for the first approach. I'm also preparing another PR for the second approach which is much simpler to implement.

[gwenneg]

#30000 and #30005 should hopefully cover everything you need @mikethecalamity and @Jojal.