Add cefas-manager repair controller

[Osvaldo Andrade (osvaldoandrade)]

Summary

• add cefas-manager with doctor, repair dry-run, guarded execute, and leader-elected controller modes
• add Kubernetes snapshot and Lease leader-election support without adding client-go
• package cefas-manager in the Docker image and Helm chart with manager Deployment/RBAC in observe mode

Validation

• go test ./...
• helm lint dist/helm/cefas
• helm template cefas-test dist/helm/cefas --namespace cefas-test
• RESULT_DIR=/tmp/cefas-bench/cefas-manager-repair-rf3-standard PROJECT=cefas-manager-rf3 REPLICATION_FACTOR=3 scripts/bench/bench_8node_matrix.sh
  • write_only: 57,736,500 writes, 191,938/s, 0 errors
  • read_only: 34,529,746 reads, 115,091/s, 0 errors
  • mixed: 29,698,000 writes at 98,778/s and 15,270,209 reads at 50,790/s, 0 errors

Closes #572
Closes #582
Closes #583
Closes #584