Added decentralized staking smart contract

[AbhinavXT]

Description

Added decentralized staking smart contract

Fixes #17

What features have been added or changed/Fixed(In Points)(Required)

• Added decentralized staking smart contract

Blockchain this work is compatible with(Required)

Ethereum

Type of change(Required)

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist(Required):

• My code follows the style guidelines of this project
• I have performed a self-review of my own 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

Output Screenshots(Required)