Implement user-configured suppressions

Description

Implements user-defined suppressions as described in #197 (closed)

Additions

• Per-job configuration detection and loading
• From this configuration, suppressions are registered
• Entities matching this suppression are removed from the entity tree
• A new base path field for FileEntities to get both the absolute and relative names

Changes

• Everything to make the above work

Test and Review

To be filled in by the reviewers

• All of the methods are commented to expectation

• The methods are tested to satisfaction

• There are no unnecessary files present in the MR

• The continuous integration has no problems with the MR

• The MR is filled in as requested (including labels, milestones, and reviewers)

• The documentation is up-to-date

• All nullable parameters are marked as such