Tracking: Support human-readable duration format in CRDs

[sbernauer]

I AS A USER want to not put in random big integer numbers in CRDs such as terminationgraceperiodseconds: 8763762374, but instead want to have some human readable duration such as terminationgraceperiod: 42h.

I AS A STACKABLE DEVELOPER want to not implement this in all operators, so have it in operator-rs

Requirements

1. Must: Try to stick to the k8s way of specifying durations. It is ok to omit or add more features if this makes sense. In general its always easy to add new features, and hard to remove them again.
2. Must: Having support for s,m,h,d,w
3. Could: Having support for M,y as the implementation is more complicated but we might need this for ca certificate lifetime.
4. Could: Millisecond support
5. Must NOT: Support long variants 5seconds or 42minutes. K8s does not support this as well
6. Should: You should be able to do all the stuff std::time::Duration supports

Implementation decisions

• Custom struct Duration with inner type std::time::Duration
• impl Deref for Duration with Target = std::time::Duration
• operators should use the Duration struct everywhere in their code possible and prefer that over std::time::Duration so that, for example, log messages are consistent to the k8s way of formatting durations.

Implementation checklists

Tasks

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1. feat: Add support for human-readable duration formats #647
   2 of 7
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2. Release 0.50.0 #654
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3. refactor: Use new Duration struct from operator-rs trino-operator#474
   5 of 12
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4. feat!: Add op impls, UTC helper function and interop with time crate for Duration #671
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5. feat: Add duration doc page documentation#467
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Operator Tasks

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1. refactor: Use operator-rs Duration airflow-operator#333
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2. refactor: Use operator-rs Duration druid-operator#478
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3. refactor: Use operator-rs Duration hbase-operator#401
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4. refactor: Use operator-rs Duration hdfs-operator#408
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5. refactor: Use operator-rs Duration hive-operator#378
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6. refactor: Use operator-rs Duration spark-k8s-operator#292
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7. refactor: Use operator-rs Duration superset-operator#412
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8. refactor: Use operator-rs Duration zookeeper-operator#733
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9. refactor: Use operator-rs Duration opa-operator#483
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10. feat: Make cert lifetime configurable secret-operator#306
    4 of 11
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11. refactor: Use operator-rs Duration listener-operator#115
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