[BUG] Interpolation of ThisFile doesn't work in the config section

[kjczarne]

Describe the bug
The interpolation of $(ThisFile) placeholder doesn't work in the config section.

To Reproduce
Steps to reproduce the behavior:

1. Use $(ThisFile) in the config.report path.
2. The path resolves to the __file__ in the kalash module instead of the real YAML path.

Expected behavior
Path resolves to the YAML file parent directory.

Screenshots
N/A

Platform (please complete the following information):
Version: 4.0.0

Additional context
Interpolation operates on internal state of the Trigger class, piping would make more sense and would make it easier to understand where the values are interpolated.