[stakingindex] implement indexer for new staking contract

[envestcc]

Description

The new version of the staking contract is coming, mainly removing the restrictions on the staking amount, embracing liquidity-hub better. Therefore a new indexer is also required.

Three main changes:

• add a common pkg pkg/util/abiutil to handle data structure convertion between contract and go
• add indexer common to implement some basic for all contract indexers
• add the new staking indexer for the new staking contract

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [] make test
• [] fullsync
• [] Other test (please specify)

Test Configuration:

• Firmware version:
• Hardware:
• Toolchain:
• SDK:

Checklist:

• [] My code follows the style guidelines of this project
• [] I have performed a self-review of my code
• [] I have commented my code, particularly in hard-to-understand areas
• [] I have made corresponding changes to the documentation
• [] My changes generate no new warnings
• [] I have added tests that prove my fix is effective or that my feature works
• [] New and existing unit tests pass locally with my changes
• [] Any dependent changes have been merged and published in downstream modules

[sonarcloud]

Quality Gate failed

Failed conditions
4.9% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud