Normalize: split into Normalize and Remove Batch Effects

[BlazZupan]

Split the widget to Normalize and Remove Batch Effects. Currently only model-based batch effect removal will be supported, but we should add canonical correlation analysis-based batch effect removal as well. With such and similar additions, it would be better to have two widgets. Plus, this will make batch effect removal step, a crucial step under mutli-sample data sets, explicit in the workflow.