Move challenge-toolkit to CLI install instead of submodule

[The0mikkel]

Move the challenge-toolkit to use CLI install system, instead of requiring it as a submodule.

This makes it more widely accessible, making it easy to upgrade and maintain compatibility and use.
However this requires that the documentation and current integration is changed.

To do:

• Identify areas, where installed CLI tool might be heavy or impractical
• Change template implementation to use CLI tool install
• Change documentation to reflect change in CLI tool
• Change CI to use CLI tool installed instead of as a submodule

Dependency

This feature requires the following to be completed:

• Add python CLI package release challenge-toolkit#1