feat: add subscribe flag and event listener

[neutrinoks]

Description

This PR attacks an existing bug in the polkadot-SDK, where subscribing to finalized block events won't be returned in any case. A flag has also been added to decide whether one wants to wait for the finalization of the sent extrinsic.

To workaround the existing bug mentioned in paritytech/subxt#1668, we are now manually listening to events and filtering them for the expected event. A couple of conversions are obsolete by returning the expected event directly. Contained event data can be accessed directly.

Before, one always had to wait for the finalization of the sent extrinsic. Now, one can choose between sending only (not waiting for the extrinsic's result) and waiting for finalization and returning the event and block hash.

Extensive testing on these changes is too much and heavy for one PR - therefore, it has been skipped. The new wait-for-finalisation-flag and the new CLI option --skip-finalisation have been evaluated manually. See follow-up tasks.

maat's real_world_use_case has also been fixed until the step about submitting the windowed PoSt. See #477.

There are multiple follow-up tasks:

• Maat: Failing test InvalidPoRepProof #477
• Storagext: Check for extrinsic/event filter simplifcation #478
• Storagext: Implement custom pallet-error catching and returning #480
• Runtime: harmonize extrinsic calls emitting events #486

Solves: #415, #381.

Checklist

• Make sure that you described what this change does.
• Are there any follow-up tasks? See description above.
• Have you tested this solution?
  • Yes and no, see description.
• Were there any alternative implementations considered?

[jmg-duarte]

The current PR is much larger in scope in comparison with the issue.

The ideas are clearly here, but the PR needs to be trimmed down.

[jmg-duarte]

Needs to be drastically simplified.