[DO NOT MERGE] feat: add support for current sidechain design

[mvadari]

High Level Overview of Change

This PR adds support for the latest version of the sidechain design. It also removes the helper methods that were used for the previous version, since those are no longer needed.

There are 7 new transaction types:

• XChainCreateBridge (creates a new cross-chain bridge)
• XChainCreateClaimID (creates a new cross-chain claim ID)
• XChainCommit (locks/burns the funds on the source chain)
• XChainClaim (claims the transfer funds on the destination chain)
• XChainAddAttestation (submits an attestation from a witness server) (insides might be modified in the future)
• SidechainXChainAccountCreate (creates an account on the destination chain) (to be renamed)
• XChainModifyBridge (modifies the properties of a cross-chain bridge)

Context of Change

sidechain prod release

Type of Change

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)

Before / After

Test Plan

Tests were added for all the new features. CI passes.

Future Tasks

• Better documentation for the new models
• Add more tests