Upgrade pickaxe code to groovy version 4

[thomashartm]

Groovy 4 comes with a plethora of interesting new features which presents a number of opportunities for the whole framework:

• Groovy Contracts
• Records for pure DTOs
• POJO annotation for integration with java

This comes with the chance of a refactoring the stack to a more flexible setup

• Move out HTTP client, so that the runner decides which lib to use
• Introduce Apache HTTP 5
• Separate into core lib and runners (maven, CLI, burp)
• New burp runner (for authenticated scans) .. maybe this one deserves a separate project
• Refactor all existing checks to YAML (Optional)