make module_order take into account parent_id from scanned custom data.

[jdcla]

Description of feature

Currently, it does not seem possible to order figures for custom data with those of pre-existing modules. Otherwise, achieving this has not been properly documented.

My current approach incorporates all plot info within custom data formats ending in _mqc.{ext}.
The expectation is that module_order defined within the loaded config file takes into account the parent_id listed in these custom data formats. The current behavior seems to ignore this and presents all custom data at the top of the report.

I have currently not found a working solution.