Add an updated version of Polimec's Runtime

[lrazovic]

This PR adds a Polimec "skeleton" runtime.

It's basically a fork of Substrate Cumulus Parachain Template, updated to polkadot-v0.9.42, but we also have:

• Two instances of pallet_assets, one representing the "local" assets and another one to store the assets from a "trusted reserve".
• A pallet_funding instance (and all the required pallets - like the insecure-randomness-collective-flip one).

We can use this runtime as a "sandbox" to quickly test the new features coming in every update, and can be imported to use as a test runtime using xcm-emulator.

[linear]

PLMC-174 Update to 0.9.42

It includes the revamped Currency system. More on this topic:

• Tokens: Revamp locking & reserving paritytech/polkadot-sdk#236
• Deprecate Currency; introduce holds and freezing into fungible traits paritytech/substrate#12951

You can specify the different "Hold Reasons" in the runtime:

• https://github.com/paritytech/substrate/blob/master/bin/node/runtime/src/lib.rs#L441
• https://github.com/paritytech/substrate/blob/1073f458389c31b434f1302a90242e28ca3f8f09/frame/balances/src/lib.rs#L261

Can be useful to improve our locking system.

[JuaniRios]

Tests pass and node gets correctly spawned with the new zombienet config.

Just one test is failing due to the new traits on pallet_balances.
Instead of trying to fix them, I suggest we merge this so I can change the Currency traits for the Fungible ones, and then make all tests pass.