feat(devnet): add ISMP

[peterwht]

This PR adds ISMP to the devnet runtime. The purpose is to get ISMP added to devnet to start deeper work to interface ISMP with contracts, and create more comprehensive testing.

It includes:

Devnet runtime:

• ISMP pallet
• removed: Demo pallet

Node

• ISMP Inherent
• ISMP RPC

Test

• removed: Script to test GET request + response

Note:
In order to use ISMP, it must be built with --features ismp enabled. When this feature is enabled, both testnet and mainnet runtimes will be disabled and error with "ISMP is not enabled". If the feature is not enabled, devnet, testnet, and mainnet will be built. However, ISMP will not work for devnet.

Because the node requires that the runtimes implement the runtime API, we must feature-gate with the ISMP feature. Unfortunately, because trait aliases are experimental (nightly) feature-gating is rather verbose allowing us to remain on stable.

Updated CI PR here: #276

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 129 lines in your changes missing coverage. Please review.

Project coverage is 51.47%. Comparing base (b653091) to head (dc56b5f).

Files with missing lines	Patch %	Lines
runtime/devnet/src/lib.rs	0.00%	64 Missing ⚠️
node/src/rpc.rs	0.00%	24 Missing ⚠️
node/src/service.rs	0.00%	22 Missing ⚠️
runtime/devnet/src/config/ismp.rs	0.00%	9 Missing ⚠️
node/src/chain_spec.rs	0.00%	8 Missing ⚠️
node/src/command.rs	0.00%	2 Missing ⚠️

@@            Coverage Diff             @@
##             main     #270      +/-   ##
==========================================
- Coverage   52.22%   51.47%   -0.76%     
==========================================
  Files          47       48       +1     
  Lines        4823     4894      +71     
  Branches     4823     4894      +71     
==========================================
  Hits         2519     2519              
- Misses       2255     2326      +71     
  Partials       49       49              

Files with missing lines	Coverage Δ
node/src/command.rs	0.00% <0.00%> (ø)
node/src/chain_spec.rs	9.47% <0.00%> (-0.26%)	⬇️
runtime/devnet/src/config/ismp.rs	0.00% <0.00%> (ø)
node/src/service.rs	0.00% <0.00%> (ø)
node/src/rpc.rs	0.00% <0.00%> (ø)
runtime/devnet/src/lib.rs	5.53% <0.00%> (-0.92%)	⬇️

[peterwht]

[sc-151]

[evilrobot-01]

LGTM, but my preference would be to not merge in the demo stuff, but rather separate it out into a branch/draft PR which can be used for any testing required and as an easy reference for our own implementation.

[peterwht]

To document here, the demo pallet was removed from this PR. Testing ISMP can utilize the following branch (which will never be merged into main). #293

[evilrobot-01]

Just one last tweak please - by adding the mentioned pallet into the benchmarks list now we should hopefully not miss it when progressing to testnet, provided we do a simple diff of the runtimes.

[Daanvdplas]

Very exciting! Left one comment but no reason to wait with merging