* initial staking pallet
* add staking pallet to runtime
* support session rotation for serai
* optimizations & cleaning
* fix deny
* add serai network to initial networks
* a few tweaks & comments
* fix some pr comments
* Rewrite validator-sets with logarithmic algorithms
Uses the fact the underlying DB is sorted to achieve sorting of potential
validators by stake.
Removes release of deallocated stake for now.
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Co-authored-by: Luke Parker <lukeparker5132@gmail.com>
