Stake locks extracted out of TokenStaking into a library

[pdyraga]

This change allows us to save some bytecode space in TokenStaking for top-ups implementation. The contract size went down from 24926 to 22409 (-2517 bytes).

I have also introduced initTokenStaking function in initContracts.js to keep the details about TokenStaking library linking and deployment there and not pollute every unit test with the same logic.

Last but not least, LockUtils library has been moved to sit next to Locks library.

[pdyraga]

const TokenStaking = artifacts.require("TokenStaking.sol");

module.exports = async function() {
    let instance = await TokenStaking.deployed();

    let bytecode = instance.constructor._json.bytecode;
    let deployedBytecode = instance.constructor._json.deployedBytecode;
    
    let bytecodeSize = bytecode.length / 2; // size in bytes
    let deployedBytecodeSize = deployedBytecode.length / 2; // size in bytes

    console.log(
      "TokenStaking size of bytecode in bytes = ", 
      bytecodeSize
    );
    console.log(
      "TokenStaking size of deployed bytecode in bytes = ", 
      deployedBytecodeSize
    );
    console.log(
      "TokenStaking initialization and constructor code in bytes = ", 
      bytecodeSize - deployedBytecodeSize
    );
}

Before:

TokenStaking size of bytecode in bytes =  24926
TokenStaking size of deployed bytecode in bytes =  24434
TokenStaking initialization and constructor code in bytes =  492

After:

TokenStaking size of bytecode in bytes =  22409
TokenStaking size of deployed bytecode in bytes =  21919
TokenStaking initialization and constructor code in bytes =  490