Extend the already implemented FreeSurfer segmentation, so that it can automatically detect and exploit T2-weighted scan (in addition to the default T1-weighted scan) for multimodal segmentation

[malinINCF]

No description provided.

[tiborauer]

As a first step, @imraniac implemented automatic detection and processing of T2 stream.
It seems Freesurfer cannot autodetect the imported images, and it requires explicit instruction. Therefore, the next step should be to investigate the merging aamod_freesurfer_initialise and aamod_freesurfer_autorecon_all into a single module, which allows more control over input data.