Make the flake more modular

[shard77]

Hey, would you consider adding more modularity/customization to the flake?

So that for ex. the user could choose the specific category of tools to install/use (web-pentesting, reverse-engineering, etc..).
IMO it would be a great idea, so that people can just add the flake on top of their existing configuration and use a specific set of packages.
Also, would you consider adding more tools that are blue-team oriented, or is this flake solely for red-teamers?

It could also be a nice idea to add options to use the full environment, or to use the flake onto an existing system (although this could already be done, it's not really practical since you need to modify the flake manually)