Add ability to customize the Micrometer MeterRegistry

[nscuro]

Micrometer allows for customization of its MeterRegistry via MeterFilters.

Filters can be used for various things, but one important capability is to omit, rewrite, or add tags to all metrics.

In order for MeterFilters to work, they need to be registered before all Meters. Because Alpine does a large chunk of initialization at class loading time, it is currently not possible to add filters in a way that guarantees that they'll be applied to all Meters.

ExecutorService metrics for example are registered in a static { } block. If the EventService class is loaded prior to the class adding filters to the registry, the filters will not be applied to ExecutorService metrics.

Alpine/alpine-infra/src/main/java/alpine/event/framework/EventService.java

Lines 53 to 56 in 7615930

	EXECUTOR = Executors.newFixedThreadPool(ThreadUtil.determineNumberOfWorkerThreads(), factory);
	INSTANCE.setExecutorService(EXECUTOR);
	INSTANCE.setLogger(LOGGER);
	Metrics.registerExecutorService(EXECUTOR, EXECUTOR_NAME);

Provide a mechanism similar to Spring Boot's MeterRegistryCustomizer.