feat: support ns offload policy

[ericsyh]

(If this PR fixes a github issue, please add Fixes #<xyz>.)

Fixes #235

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This change added tests and can be verified as follows:

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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[ericsyh]

Test record

apiVersion: resource.streamnative.io/v1alpha1
kind: PulsarNamespace
metadata:
  name: test-ns
  namespace: resource
spec:
  name: test-tenant/testns
  connectionRef:
    name: pulsar-connection
  retentionTime: 20h
  retentionSize: 2Gi
  offloadThresholdTime: 10h
  offloadThresholdSize: 5Gi

pulsar-admin namespaces get-offload-policies test-tenant/testns
{
  "offloadersDirectory" : "./offloaders",
  "managedLedgerOffloadMaxThreads" : 2,
  "managedLedgerOffloadPrefetchRounds" : 1,
  "managedLedgerOffloadThresholdInSeconds" : 36000,
  "managedLedgerOffloadThresholdInBytes" : 5368709120,
  "managedLedgerOffloadedReadPriority" : "TIERED_STORAGE_FIRST",
  "managedLedgerExtraConfigurations" : { },
  "s3ManagedLedgerOffloadMaxBlockSizeInBytes" : 67108864,
  "s3ManagedLedgerOffloadReadBufferSizeInBytes" : 1048576,
  "s3ManagedLedgerOffloadRoleSessionName" : "pulsar-s3-offload",
  "gcsManagedLedgerOffloadMaxBlockSizeInBytes" : 67108864,
  "gcsManagedLedgerOffloadReadBufferSizeInBytes" : 1048576,
  "s3Driver" : false,
  "gcsDriver" : false,
  "fileSystemDriver" : false
}