[FIX] add "dir" to the list of func entities

[Remi-Gau]

dir was not listed as one of the entities for the func modalities.

This led to some bug on our side: cpp-lln-lab/bidspm#194

The func name template is this one:

sub-<label>[_ses-<label>]_task-<label>[_acq-<label>][_ce-<label>][_dir-<label>][_rec-<label>][_run-<index>][_echo-<index>]_<contrast_label>.nii[.gz]

The current entities we support are:

    func_entities = {'sub', ...
                     'ses', ...
                     'task', ...
                     'acq', ...
                     'rec', ...
                     'fa', ...
                     'echo', ...
                     'inv', ...
                     'run', ...
                     'recording', ...
                     'meta'};

I see quite a few other mismatch in there. @gllmflndn am I missing something or shouldn't we also:

• add ce
• remove fa, inv, recording

[Remi-Gau]

Also we only support bold as contrast label for now and cbv and phase are also in the specs.

This seems more of an edge case at the moment and might require more coding that could be rendered moot when we have a schema to help us. So I would suggest that we open an issue for this point (to remind ourselves and let others know we know) but do not move on to fix it right away.

[Remi-Gau]

Unless I am mistaken there is no dataset in bids-example with a dir entity so there is no convenient way to add a test for this one.

So I will merge for now and make a note to add a test for this... Later.