buffer: add revision ring buffer

[yedou37]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR adds a shared revision-ordered ring buffer utility to k8s.io/utils/buffer.

The motivation comes from review feedback on kubernetes/kubernetes#138338, where the snapshot ring buffer implementation in apiserver was requested to align more closely with etcd's cache ring buffer so that the implementation can eventually be shared between Kubernetes and etcd.

The new utility:

• keeps entries ordered by revision
• supports binary-search-based iteration boundaries
• supports removing entries older than a given revision
• supports explicit capacity growth while preserving logical order
• keeps the internal layout and iteration/search structure close to etcd's cache/ringbuffer.go

Why this is needed:

The existing k8s.io/utils/buffer utilities cover generic fixed-size and growing ring buffers, but they do not provide the revision-aware semantics needed by the Kubernetes snapshot storage use case, such as revision-ordered lookup and trimming by revision.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

This utility is extracted from the ring buffer work proposed in kubernetes/kubernetes#138338.

Related etcd context:

• etcd-io/etcd#21676
• etcd-io/etcd#21616

The implementation is intended to stay close in spirit to etcd's cache ring buffer while also covering the revision-aware operations currently needed by the Kubernetes snapshot storage use case.

Release note:

NONE

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[yedou37]

/cc @dims @serathius