New parachain runtime skeleton (#1158)

* file structure and initializer skeleton

* ensure session changes happen before initialization

* add a couple tests for initializer flow

* integrate with session handling

* configuration update logic

* configuration methods

* move test mock to its own module

* integrate configuration into initializer

* add note about initialization order

* integrate configuration module into mock

* add some tests for config module

* paras module storage

* implement paras session change operation

* amend past code pruning to fully cover acceptance period

* update guide again

* do pruning of historical validation code

* add weight to initialization

* integrate into mock & leave notes for next session

* clean up un-ended sentence

* alter test to account for double index in past code meta

* port over code-at logic test

* clarify checking for conflicting code upgrades

* add genesis for paras, include in mock, ensure incoming paras are processed

* note on return value of `validation_code_at`

* implement paras routines from implementor's guide

* bring over some existing tests and begin porting

* port over code upgrade tests

* test parachain registration

* test code_at with intermediate block

* fix warnings

* clean up docs and extract to separate struct

* adjust implementor's guide to include replacementtimes

* kill stray println

* rename expected_at to applied_after

* rewrite ParaPastCodeMeta to avoid reversal

* clarify and test interface of validation_code_at

* make FutureCode optional

* rename do_old_code_pruning

* add comment on Option<()> to answer FAQ

* address some more grumbles

polkadot/Cargo.lock

@@ -4457,6 +4457,48 @@ dependencies = [
  "trie-db",
 ]
 
+[[package]]
+name = "polkadot-runtime-parachains"
+version = "0.8.0"
+dependencies = [
+ "bitvec",
+ "frame-benchmarking",
+ "frame-support",
+ "frame-system",
+ "hex-literal",
+ "libsecp256k1",
+ "log 0.3.9",
+ "pallet-authorship",
+ "pallet-babe",
+ "pallet-balances",
+ "pallet-offences",
+ "pallet-randomness-collective-flip",
+ "pallet-session",
+ "pallet-staking",
+ "pallet-staking-reward-curve",
+ "pallet-timestamp",
+ "pallet-treasury",
+ "pallet-vesting",
+ "parity-scale-codec",
+ "polkadot-primitives",
+ "rustc-hex",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "sp-api",
+ "sp-application-crypto",
+ "sp-core",
+ "sp-inherents",
+ "sp-io",
+ "sp-keyring",
+ "sp-runtime",
+ "sp-session",
+ "sp-staking",
+ "sp-std",
+ "sp-trie",
+ "trie-db",
+]
+
 [[package]]
 name = "polkadot-service"
 version = "0.8.2"