Refactor task scripts following TDD principles

[sophie22]

With the exception of snr_map and largely the ACR tasks scripts, most tasks do not follow software development best practices. This makes the code unnecessarily convoluted, difficult to debug/test and expand with new features.

Test-driven development and refactoring should be implemented. Updating the hazenlib tasks following object-oriented principles will result in a code that is easier to understand, use, test and productionise.

• review existing code and identify common functions that can be made into the shared utilities
• refactor each task script with OOP and TDD principles, which will improve the test coverage as well (currently only 72%)
• simplify scripts and functions where possible
• make variable names more verbose, descriptive and standardised across scripts