Support for pre-computed BUSCOs must follow the structure from sanger-tol/restructurebuscodir

[muffato]

Description of feature

We'll be using sanger-tol/busco to run all necessary BUSCOs, and then sanger-tol/blobtoolkit's ability to read pre-computed BUSCOs. However this feature is not absolutely compatible with the standard structure of BUSCO results from the sanger-tol/restructurebuscodir module.
Need to fix that