[WIP] Mesh 1868 chain extension

[Neopallium]

changelog

new features

• Add support for Smart contracts to call into the runtime and read from storage.

modified API

• Add CallRuntime, ReadStorage, GetSpecVersion, GetTransactionVersion chain extensions.

[codecov[bot]]

Codecov Report

Merging #1337 (4d68565) into develop (1d4fb5a) will increase coverage by 0.09%. The diff coverage is n/a.

:exclamation: Current head 4d68565 differs from pull request most recent head 3582ade. Consider uploading reports for the commit 3582ade to get more accurate results

@@             Coverage Diff             @@
##           develop    #1337      +/-   ##
===========================================
+ Coverage    43.90%   43.99%   +0.09%     
===========================================
  Files          140      140              
  Lines        30049    30049              
===========================================
+ Hits         13193    13221      +28     
+ Misses       16856    16828      -28     

Impacted Files	Coverage Δ
pallets/multisig/src/lib.rs	38.92% <0.00%> (+0.22%)	:arrow_up:
pallets/identity/src/lib.rs	16.54% <0.00%> (+0.58%)	:arrow_up:
pallets/settlement/src/lib.rs	48.17% <0.00%> (+1.71%)	:arrow_up:

[Neopallium]

TODOS:

• [x] Add benchmarks for new chain extension interfaces (ReadStorage, GetSpecVersion, GetTransactionVersion, etc...)
• [x] Add call filter and storage + extrinsics for managing the list of allowed runtime calls.
• [x] Add helper functions to chain extension: GetKeyDid(AccountId), TwoX hasher.
• [ ] Optional - Add unit tests for chain extension weights.