Update to Polkadot-sdk 1.6.0 - Pendulum

[gianfra-t]

Related to master ticket tasks/#419

We need to perform the upgrade of Pendulum to polkadot-sdk release v1.6.0.

This involves updating all corresponding dependencies in this repository:

• Self-maintained pallets
• Chain extension code
• Runtimes (Including storage migrations)
• Node client

Before performing the runtime upgrade with this changes it is essential to have checked which are the necessary migrations and added the migration code, if needed.

[prayagd]

Hey team! Please add your planning poker estimate with Zenhub @b-yap @ebma @gianfra-t @TorstenStueber