HDDS-9200. [Snapshot] Added logs and metrics for snapshot purge and set property APIs

[hemantk-12]

What changes were proposed in this pull request?

For snapshot purge and set snapshot property, there is no OM log or audit log. Without logs, it is hard to debug an issue like Snapshot chain corruption (e.g. HDDS-10524).

This change is to add logs so that, there is a way to know which snapshot is updated by which request. It also adds metrics for SnapshotPurgeRequest and SetSnapshotPropertyRequest APIs for monitoring purposes.

What is the link to the Apache JIRA

HDDS-9200

How was this patch tested?

Updated existing unit tests to validate that metrics are populated correctly.