Add memory accounting to exponential histogram library.

[JonasKunz]

Implements memory accounting (Accountable) and circuit breaker support for the exponential histogram library added in #131220. Just like the T-Digest library, the circuit breaker is abstracted away through an interface, so that no direct dependency on it is required for the lib.

This PR now defines for the ExponentialHistogramMerger that if the result is queried, the merger is cleared and the caller takes ownership of the returned histogram. Therefore the caller is then responsible for correctly calling close() on the returned histogram.

I was hesitant of doing it this way, because when implementing the ES|QL support this might cause unnecessary allocations:

E.g. for a query like | STATS PERCENTILE(MERGE(responseTime), 0.9) by service.name, TBUCKET(1m) it might be more efficient if we can reuse the ExponentialHistogramMerger across the aggregation groups. In this case this would mean merging all histograms for the first service.name, query the percentile and then continue with the next group. It would be ideal if the PERCENTILE could operate on a histogram instance "lent" from the merger, so that it can be reused then for the next group instead of requiring a new allocation.
However, if this is actually useful we can add this behaviour later when we get to the ES|QL implementation.

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)