[Feature Request] - Allow folder structure for a reconciliation template

[Benjvandam]

Description of the issue
Platform clients showed that they created structure in the parts of their templates by creating folders. This would be interesting to try out for more complicated templates (such as immovable income in Belgium PIT package). This folder structure would potentially break the toolchain CLI.

Describe the solution you'd like
Find out if and why the toolchain CLI would not work with subfolders within a template folder, and refactor it so that it would work.

Describe alternatives you've considered
I don't really see an alternative except for not implementing this folder structure

[robindeclercq]

Also see: #136