Milestone 1: Ensure Solang works with latest Substrate

[xermicus]

Solang was developed against Substrate v3.0 and older versions of both the npm polkadot api and the contract metadata crate. They need to be updated to the latest versions, and any consequent issues will need to be resolved.

The Substrate integration tests at: https://github.com/hyperledger-labs/solang/tree/main/integration/substrate use various polkadot npm libraries, must all be updated to the latest version, and any consequent issues must be resolved. Success for this milestone is simply that the tests are upgraded to the latestversions of all the substrate components and the tests pass, in a pull request to solang repository and any review comments are addressed.

Status

• [ ] Update Integration tests
  • [x] Update existing test suite and use up-to-date production substrate node: #931
  • [ ] Fix any remaining regressions
  • [ ] Integrate and use subxt for integration tests: #990
• [ ] Various bug fixes and changes in solang to better align with substrate
  • [x] #999
  • [ ] #1006
  • [x] #1011
  • [ ] Fix anonymous values in return types
  • [ ] Update calls to the seal API to reflect latest versions: #1022
• [ ] Re-use ink_metadata for ABI generation: #989
  • [ ] Allow scale-info to be used at runtime
  • [ ] Allow ink_metadata to be used at runtime
  • [x] Since the ink! storage refactor, ink_metadata requires nightly rust. We must be able to compile with stable rust (without RUSTC_BOOTSTRAP). Potential fix