Staking pallet (#373)

* 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.

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

Cargo.lock

@@ -8386,7 +8386,6 @@ dependencies = [
 name = "serai-primitives"
 version = "0.1.0"
 dependencies = [
- "lazy_static",
  "parity-scale-codec",
  "scale-info",
  "serde",
@@ -8504,6 +8503,7 @@ dependencies = [
  "scale-info",
  "serai-in-instructions-pallet",
  "serai-primitives",
+ "serai-staking-pallet",
  "serai-tokens-pallet",
  "serai-validator-sets-pallet",
  "sp-api",
@@ -8522,6 +8522,22 @@ dependencies = [
  "substrate-wasm-builder",
 ]
 
+[[package]]
+name = "serai-staking-pallet"
+version = "0.1.0"
+dependencies = [
+ "frame-support",
+ "frame-system",
+ "pallet-session",
+ "parity-scale-codec",
+ "scale-info",
+ "serai-primitives",
+ "serai-validator-sets-pallet",
+ "serai-validator-sets-primitives",
+ "sp-runtime",
+ "sp-std",
+]
+
 [[package]]
 name = "serai-tokens-pallet"
 version = "0.1.0"
@@ -8554,12 +8570,14 @@ dependencies = [
  "frame-support",
  "frame-system",
  "hashbrown 0.14.0",
+ "pallet-session",
  "parity-scale-codec",
  "scale-info",
  "serai-primitives",
  "serai-validator-sets-primitives",
  "sp-application-crypto",
  "sp-core",
+ "sp-io",
  "sp-runtime",
  "sp-std",
 ]