Add metrics about PooledByteBufAllocator

[Bue-von-hon]

Motivation:
Add metrics related to PooledByteBufAllocator that are already exposed by the netty.

Modifications:

• The PooledByteBufAllocator metric is now available in MoreMeterBinders.
• To expose the PooledByteBufAllocator metrics, created the PooledByteBufAllocatorMetrics class.

Result:
Enables the PooledByteBufAllocator metric.
this close #2633.

[github-actions]

🔍 Build Scan® (commit: bcf690f)

Job name	Status	Build Scan®
build-ubicloud-standard-8-jdk-8	✅	https://ge.armeria.dev/s/izkwxmpenhmka
build-ubicloud-standard-8-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/52zlr3lubbxlk
build-ubicloud-standard-8-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/qewknnyjo65kq
build-ubicloud-standard-8-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/otrza4xxchxv4
build-ubicloud-standard-8-jdk-17-leak	✅	https://ge.armeria.dev/s/iu3ediwguebpm
build-ubicloud-standard-8-jdk-11	✅	https://ge.armeria.dev/s/dgkfmugcnkhfc
build-macos-12-jdk-21	✅	https://ge.armeria.dev/s/4776b2nmum762

[jrhee17]

Micrometer already provides bindings to Netty Metrics (ref: https://docs.micrometer.io/micrometer/reference/reference/netty.html)

I prefer that we either:

1. We close this issue and allow users to add metric bindings themselves. Adding the metric bindings is not difficult and the scope of applying this metric seems ambiguous
2. We add bindings for servers only by default. The name will probably be a combination of local address + ports.

Let me know what you think @line/dx

[ikhoon]

I didn't know that Netty metrics were supported by Micrometer finally.

I prefer automatically setting the metric for the default one (ByteBufAllocator.DEFAULT) when the MoreMeterBinders class is loaded.