* feat(s3): add four bucket configuration handlers
- GetBucketPolicyStatus: computes IsPublic from the existing bucket policy
- PutBucketRequestPayment: companion writer to the existing GET; accepts
only BucketOwner
- GetBucketAccelerateConfiguration: returns <Status>Suspended</Status>
- GetBucketLogging: returns an empty BucketLoggingStatus
Lets AWS SDK probes succeed instead of returning MethodNotAllowed.
* review: route GetBucketPolicyStatus through checkBucket
Mirrors the existence/auth gating used by other bucket handlers and
drops the bespoke filer_pb lookup so NoSuchBucket precedence is
consistent across the API surface.
* review: cap PutBucketRequestPayment body with MaxBytesReader
The body is unmarshalled as RequestPaymentConfiguration, which is a
handful of bytes; reject excessively large payloads up front and
defer Close immediately after wrapping.
* review: gate static getters on checkBucket
GetBucketAccelerateConfiguration and GetBucketLogging now run the
standard bucket existence check before returning the static
Suspended / empty-status response so a missing bucket cannot appear
to have valid configuration.
* review: share cache helper across misc tests; check io.ReadAll error
Accelerate and Logging tests now run through newMiscTestServer like
the others so the checkBucket guard sees a cached bucket; the
ReadAll error is explicitly checked.
