Add optional pod quota counter strategy #2231

Feature description

Improve pod quota performance with a new strategy using a pod quota counter

1. use du when available to calculate the pod size
2. create a pod counter file to be updated at each write this avoid point 1 on each Write
3. as a security use a maxAge parameter to decide a full recalculation on Write : 24h by default

The actual default pod-quota-file.json is kept
An optional quota/pod-quota-counter.json component is available and can be added

"import": [
      "css:config/storage/backend/pod-quota-file.json",
      "css:config/storage/backend/quota/pod-quota-counter.json",
]

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