Refactor and clean up the deployment shell scripts

[matjazv]

Description

Refactor and clean up the deployment shell scripts (1_deployTokenContracts.sh, 2_deployStakingAndGovernance.sh, etc.).
Extract common code and logic into functions and use them instead of repeated code inside each of these scripts. Also, the if..else..fi code blocks can be refactored as it's mentioned in the reference below.

Related messages and conversation for a reference is available here.

Motivation

After the refactoring, the code will be easier to read and maintain, and it will overall be more cleaner.