Draft total fixed issuance missed rewards

[paulormart]

This example calculates the missed rewards related to the change of total fixed issuance on asset-hub-polkadot between eras 1981 and era 1986. (note end_block_number should be replaced when runtime/2000002 becomes enacted on Polkadot).

It will also output a csv file containing all validators, rewards and respective reward destination account.

Run with cargo run --example=storage_calculate_total_issuance_rewards

Running `target/debug/examples/storage_calculate_total_issuance_rewards`
Iterating over 68044 blocks
Processed 0%, 68044 blocks still to go.
Processed 50%, 34022 blocks still to go.
Calculated total missed rewards: 1185347.8354230456 DOT for 22315 accounts (110.8426263s)

List of accounts and respective rewards
total_issuance_rewards.csv

Preimage for a batch_all extrinsic containing all treasury.spend calls
validated_batch_calls.csv