Update IPAM pool monitor's pool state logic and language

[rbtr]

Reason for Change:

• Standardize the language for the CNS IP pool:
  • "Allocated": all IPs that CNS has been allocated by DNC.
  • "Assigned": the IPs that CNS has assigned to specific Pods.
  • "Unassigned": allocated - assigned.
• Defines additional data types for modelling IP pool information:
  • ipPoolState: is the live view of the IP pool; IPs allocated, assigned, requested, available, pendingProgramming, pendingRelease, unavailable, notInUse.
  • metaState: holds pool metadata: the batch size, max size, and min/max free.
  • adds helper methods to build this state from a single query of the CNS pool singleton instead of several locking calls.
• Upcast all the numerics in the pool Monitor to int64 to stop converting and comparing back and forth between int/int64
• Update the IPAM metrics to align with these changes.

Issue Fixed:

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests

Notes:

[rbtr]

@huntergregory @thatmattlong what happened?

[huntergregory]

@huntergregory @thatmattlong what happened?

Not sure what it means by this:

huntergregory dismissed thatmattlong’s stale review via 7cc1297 17 hours ago

I made some commits to #1138 last night, but why would that impact this?

[rbtr]

Unclear...GitHub thinks you pushed a commit to this branch I think? @thatmattlong no change since your review, do you mind stamping it again