imp(distribution): Add ClaimRewards transaction, interface, types and event

[Vvaradinov]

Description

This PR adds the ClaimRewards transaction, Interface definition, types and event.

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Closes ENG-2234

[linear]

ENG-2234 ClaimRewards Distribution transaction

Context

Because of the deprecation of Cosmos txs, we now want to have all dApp store interactions go through the EVM. This requires the addition of some custom extension transactions that are not default transaction in the Cosmos SDK. The proposed transaction is ClaimRewards

• Claims all rewards from all (or select) validators for a delegator address (origin of transaction)

• Iterate through all delegations of the delegatorAddress and withdraw any pending rewards

      event ClaimRewards(
          address indexed delegatorAddress,
          uint256 amount
      );
  
      // Optionally add more fields here like string[] validators to be able to pick which ones to claim from
      // If we pass an empty array for validators we can default to withdrawing from everyone
      function claimRewards(
          address delegatorAddress,
          string[] validators, 
      ) external returns (bool success);
  

[fedekunze]

LGTM, we'll need to add tests too

[Vvaradinov]

@fedekunze adding tests in separate PRs