Upgrade Polkadot SDK version to v1.6.0

[Anny0nn]

Closes #145

Using new-modified-construct-runtime atm because the diffs between the old and the new one are too big and I couldn't get InvArch runtimes to compile with the upgraded version.

Ref PRs https://github.com/paritytech/polkadot-sdk/pull/1256 chain-spec: getting ready for native-runtime-free world https://github.com/paritytech/polkadot-sdk/pull/1246 DmpQueue & XcmpQueue transition to MessageQueue https://github.com/paritytech/polkadot-sdk/pull/2048 & https://github.com/paritytech/polkadot-sdk/pull/2651 Identity pallet improvements https://github.com/paritytech/polkadot-sdk/pull/2803 cumulus-primitives-parachain-inherent split https://github.com/paritytech/polkadot-sdk/pull/2331 ExportGenesisStateCommand to ExportGenesisHeadCommand https://github.com/paritytech/polkadot-sdk/pull/1343 RuntimeTask https://github.com/paritytech/polkadot-sdk/pull/2331 Rename ExportGenesisStateCommand to ExportGenesisHeadCommand